If you’re one of the people who think BF5 is too hard, and find you get killed way too quickly whenever you play, of course leading to frustration on your part, perhaps I have some tips that may be of use to you.
All you have to do is to SPECTATE.
Focus on one map to begin with, for example Rotterdam.
In the menu, do this:
PLAY → MULTIPLAYER → ADVANCED SEARCH, then under Maps selected Rotterdam or one of the other maps.
Point is, just keep sticking to this one map to begin with.
In the list of servers that is displayed, notice there are 3 dots just to the left of the Join game button.
If you press these dots, you can select JOIN AS SPECTATOR from the menu that pops up.
Now the game loads and you’re put into Spectator-mode.
If this is your first time spectating, press O to get into preferences.
Under ”— Player View —”, find the entry for ”Player Death Transition” and select ”Same Player”.
This means you will be watching the player you select for the entire game.
Press O again to get our of preferences.
Press TAB to see the list of connected players, then click on one of the top players in either one of the teams.
If you want to play Support yourself, pick the best Support player.
If you want to play Medic yourself, pick the best Medic player.
etc. for Assault and Recon.
You will now watch how your selected player plays the game – and this is usually a great learning opportunity. I do it myself all the time.
In the bottom of the screen you can see some icons with a letter next to them.
Press F2 (I think?) to ”put yourself into your selected player’s shoes” and see what he sees etc.
Now watch how he plays the game and make mental notes of it so you can use the knowledge when you’re gonna play the map yourself.
Try this for a couple of different good-scoring players playing the class you’d like to play.
Then you can see different ways of playing the game probably – because each of us probably plays the game a little differently than the other.
Keep focusing on this one single map, be it Rotterdam or whatever map you prefer to start out with.
If you want to learn how Recon’s play on that map, use Spectate on top Recon players.
If you want to learn how Assault’s play on that map, use Spectate on top Assault players.
etc. for Medics and Supports of course.
All this Spectating means you gain knowledge of how this particular map you’ve selected is played by each class, and by different people playing each class.
Once you think you’ve gained some good knowledge of the map, try playing it yourself.
That’s basically it 
Hope it can help you getting into playing and enjoying BF5.