You need to post the exact move order or the game position or pgn.
need help with engine moves, post game analysis

My guess is that you can pin his knight at e5 against his uncastled king at e8 by playing Re1, maybe after exchanging knights at e5.

I believe this is the game that the OP is describing:
I think the engine is seeing a bishop sacrifice with crazy tactics (8. dxe5 dxe5 9. Bxf7+). I wouldn't worry about it much. The engine can see tactical lines much deeper than us ordinary humans.
(There are numerous other lines, depending on how long you let the engine analyze, but I think you get the idea.)
Notice Black's bishop on g4 is unprotected. By moving your knight you can attack that piece with your queen.
Your knight is one move away from attacking f7 but after 8.Bxf7+ Kxf7 the knight checks don't work. His queen can take on g5 and e5 is well guarded.
If you first play dxe5, however, and Black recaptures then the d and e files clear out and you will have pins working for you along the files. If Black accepts the sacrifice you can then play Nxe5+ and get your piece back on g4, winning material.
Black's best is to avoid this line and not recapture on e5, giving you a free pawn with pressure along the central files.
ok...so I'm only rated about 800 and am going over a recent game I won. Right now am still learning the open games so I start with e4 all the time. my oponent plays the philidor defense, I push c3 preparing for d4. he attacks my e4 pawn with his king knight, I castle, he takes on e4, I move rook e1, he moves knight to c5 I think, then I push d4, he retreats his knight to do d7 I think, then the engine tells me to take on e5 and I have no idea why, because the knight on d7 is protecting that square and so is his d6 pawn from the philidor. so I believe I pin his knight preparing to take on e5, and so on, but if I took according to the engine I would be 3 points up but can't see the combination. any help is appreciated