Here,White to play, I played Bg5. Lichess told me in the analysis that was inaccurate although latter on, it pointed this move out as one of the best moves. At first, he recommends me to move exf5 in the 6th move and in the next moves for White. I would like to know why it is convenient to make this capture since I do not see any benefits in capturing this pawn at any time. The link of the game is https://lichess.org/PyqeZZnQ/white#10
If the black captures in return (there's not much choice for black), you either get an open vertical
e or a nasty attack on the black King by
Qh5+ and so on.
But don't worry.
Bg5 is also not so bad move =)
In general it is dubious to put too much faith computer evaluations of less than a pawn in determining the "best" move.
In this position however I think serious thinking is required. Let's think like a human: Black has made a lot of pawn moves and is therefore behind in development. In such cases it is usually good to open the position.
Okay that suggests exf5, Now you need to "think like a Grandmaster":
6.exf5 (a) 6...exf5 enumerate candidate moves: (a1)7.Nd5 (a2)7.Bg5, etc. Things get complicated but you can see ideas based on Nd5 combined with Qe2+ and Bg5 can lead to difficulties for Black.
(b) 6...gxf5 (b1)7.Ng5 Nf6 8.Qe2!? (b1.1) 8.Qa4+ (idea 9.Qb3)...
It seems 6.exf5 looks promising, now does 6.Bg5 look as good? Well the computer gives 6...Bf6?! 1.5 to White so that doesn't make 6.exf5 better; and it says after 6...Ne7 7.exf5 gxf5. Hmmmm, on 6.exf5 it liked 6...ef5 -- because now exf5 allows Nd5. So we can force gxf with Bg5... is that what we want?
Looking at these positions which are you more comfortable playing? That is the practical question. 6.exf5 might be a fraction of a pawn better if you are a computer.