Translation:The house with the red roof is my uncle's.
I think it should be correct in English, but I feel it's slightly less literal.
In Italian, "to belong" is more literally translated as "appartenere", so that sentence in Italian should be "la casa con il tetto rosso appartiene a mio zio" (which means anyway the same thing as the original Italian sentence).
La casa con il tetto rosso ... = The house with the red roof ...
... è di mio zio = is my uncle's. -> Correct.
... è lo mio zio = is my uncle. -> But no, my uncle is not a house.
... è il mio zoo = is my zoo. -> Also no, the house is not my zoo. ;o) And note that the "lo" comes only directly before a word with z. When another word is inbetween them, the "lo" is no longer necessary.