Dungeons & Dragons very much is a game of resource management. In combat you have an economy of actions to manage, and usually you only get one main action, one bonus action, plus movement. But there are also spell slots and abilities that you can use only between 1 and X times between rests (short or long, depending on the ability), and that gives an economy of abilities over the course of the "adventuring day". What most players of D&D have realized, and what is true for Baldur's Gate 3 as well, is that the sense of urgency the story pushes is mostly fake. No, you are not going to transform into a mindflayer because you took too many long rests. And if you are like me and pick up all the potatoes and chicken lying around, you probably have hundreds of camp supplies and can easily afford the 40 supplies it needs for a long rest. Your group is strongest after a long rest, you can rest pretty much everywhere, and in consequence you absolutely should do a long rest before a major fight. You can do some minor fights and exploring with only half your spell slots left, but save often and reload / long rest / redo if you run into anything more dangerous.

Note that some character classes and builds are less susceptible to running out of resources than others. As long as a warrior has hitpoints, he can keep fighting at pretty good efficiency. If a warlock manages to keep up concentration on his hex spell, he can shoot Eldritch Blasts forever with good efficiency. Other classes have cantrips that are a lot less efficient. Vicious Mockery gives a nice debuff on enemies, but does very little damage. Which is why my bard is multiclass warlock. Shadowheart fortunately gets a Fire Bolt cantrip from her race, which depending on the saving throws and armor of the target can be more efficient than Sacred Flame. But as I said before, if cantrips are the only thing that you have left, you should really do a long rest. Short rests are mainly a quick way to heal, but otherwise are important only for warlocks. If I have a warlock spell slot remaining, I use it for Armor of Agathys, then short rest to get the slot back.

The power curve of D&D with regards to level is a weird one, and it fully translates to Baldur's Gate 3. Level 1 characters are extremely weak, but fortunately in BG3 you should reach level 2 at the end of the tutorial, or very shortly after. The next big jump in power comes at level 5: Many melee classes get a second attack, cantrips double in power, and full spellcasters get access to powerful level 3 spells like fireball. In Act I of Baldur's Gate 3 there are a few major "boss fights" which are apparently designed for the group being level 5, and which would be very hard earlier on. Again, save often, and if you run into a fight you can't win even at fully rested power, reload, and maybe level up elsewhere.

Some differences between Baldur's Gate 3 and the pen & paper 5E D&D rules are pretty obvious. For example in BG3 if you wield a weapon you are proficient with, that unlocks some special attacks, like Cleave for a Greataxe or Greatsword. Other differences in rules are more subtle, and can be overlooked if as experienced D&D player you "know" that something doesn't work in the tabletop rules, and thus you don't try it. For example in BG3 you can heal another character at a distance, even an unconscious one, by simple throwing a healing potion at him, which is very different from D&D rules.

You also need to be careful with preconceived notions about which spells and abilities are useful and not. For example in pen & paper D&D the Create Water spell is mostly useless. Baldur's Gate 3 inherited the concept of "surfaces" from Divinity Original Sin games, and water is a lot more useful here to extinguish fire or wash away acid. This is also important for character stats. Strength is more useful in BG3 for carrying capacity and jump distance than it is in pen & paper D&D. And in Baldur's Gate 3 it is a huge advantage if you make a main character which is Charisma bases, e.g. a bard, sorcerer, warlock, or paladin, because the game has a lot of dialogue options in which Charisma-based skills are very frequently used. I do more Charisma checks in one session of BG3 than I did in years of playing D&D, although if you play a highly political D&D campaign your mileage may vary on this.

The availability of items in Baldur's Gate 3 might also be very different from a typical D&D campaign. Wizards (either Gale or a player-created one) are very powerful in BG3, because you can buy scrolls at nearly every trader, thus giving the wizard a huge variety of spells compared to other classes. On the other hand I haven't seen a single full plate armor yet, thus some D&D builds relying on heavy armor are less viable in BG3 than in some D&D campaigns. I haven't tried it out yet, but rangers are potentially more useful in BG3 than in classic D&D, in part because of a very high availability of arrows with additional magic damage.

I can very much recommend Baldur's Gate 3 to players of Dungeons & Dragons, because knowing D&D rules often helps a lot. But keep in mind that there are some differences due to this being a video game.