"मेरे मामा के पास एक घोड़ा है।"

अनुवाद: My uncle has a horse.

[sahilkaswa1]

My maternal uncle has a horse

[vinaysaini]

It should be accepted, IMO :)

[pp65]

Although we usually do not specify maternal or paternal uncle when speaking in English, this is a valid translation. It has now been added as an acceptable answer.