Learn Portuguese (Portugal): O gato gosta da escova. Escova-o devagar. - The cat likes the brush. Brush him slowly.

They look and sound identical, but they play different roles here! The first escova is a feminine noun meaning 'brush'. The second Escova is the verb escovar (to brush) being used as an affirmative command.

Why is the pronoun attached with a hyphen in Escova-o instead of coming before the verb?

In European Portuguese, when you give an affirmative command, the object pronoun must attach to the end of the verb with a hyphen. If it were a negative command like 'Do not brush him', the pronoun would jump before the verb: Não o escoves.

Why do we use the pronoun -o here? Does it mean 'him' or 'it'?

It can mean either in English, but here it replaces O gato (the cat). Because gato is a masculine noun, we must use the masculine direct object pronoun -o.

Why does it say gosta da escova instead of just gosta a escova?

The verb gostar (to like) always requires the preposition de right after it. When you combine de with the feminine word for 'the' (a), they merge into the contraction da.