Besar, normalmente no es un simple beso cualquiera, sino un beso prolongado.
Kissing, usually not just a simple kiss, but a prolonged kiss.
Ejemplos (Examples):
Voy a apretar a mi novia en la sala de su casa.
I’ll kiss my girlfriend in the living room of her house.
Fui al baile con mi amiga y terminamos apretando.
I went to the dance with my friend and we ended up kissing.
Pedro me dijo que se iba a apretar a esa chica porque está muy linda.
Pedro told me he was going to kiss that girl because she is very beautiful.