montar
ride
mount
to get on (a horse)
+
-ar
verb suffix
Montar means to ride and can be thought of as mount0 (as in to get on a horse0) + -ar1 (verb suffix1).
verb
  1. ride
    To ride or get on (a horse, bicycle, etc.)
    Me gusta montar a caballo los fines de semana. // I like to ride horses on weekends.
  2. assemble
    To assemble or put together
    Tenemos que montar los muebles nuevos. // We have to assemble the new furniture.