cow – la vaca
(Pronounced bah-kah)
To remember that cow is pronounced bah-kah (vaca) in Spanish, use the following mnemonic:
The cow tried to back the car (vaca) into the garage.

Vaca is feminine, so it's la vaca. Imagine a lady riding a cow.

Examples of vaca (cow) in a sentence
La vaca está comiendo hierba en el campo.
(The cow is eating grass in the field.)
El granjero tiene diez vacas en su granja.
(The farmer has ten cows on his farm.)
La leche viene de la vaca.
(The milk comes from the cow.)