Knight vs Pawns Endgames
The knight has a critical weakness against passed pawns: it's too slow. A knight takes four moves to cross the board; a bishop does it in one. This makes knight vs pawn endgames uniquely dangerous, a single passed pawn on the opposite side can be unstoppable.
Knight vs one pawn
A knight can usually stop a single passed pawn if the knight is close enough. But a distant passed pawn, one where the knight must cross the entire board, is often a draw or even a loss. The Rule of the Square doesn't apply to knights, they zigzag.
Knight vs connected pawns
Two connected pawns on the 6th rank defeat a knight. The knight simply cannot stop both pawns simultaneously. This is a critical pattern to know: if your opponent has connected pawns on the 6th, the knight cannot save you.
Training
Practise N vs P positions against the computer. Study the critical distances, how close must the knight be to stop the pawn?