If the spread is -3 and the favorite wins by exactly 3, the bet is a push. Same for totals landing exactly on the posted number. Books set lines at half-numbers (.5) specifically to avoid pushes.
Basics
Push
A tie — the bet lands exactly on the number. Stake is returned, no win or loss.
Example
Spread -7, final margin 7 → push. Total 224.5 can never push.