、。
My grandpa usually eats breakfast at six.
Literal
I [of-の] grandpa [topic-は], usually [topic-は] 6 o'clock [at-に] breakfast [object-を] eats.
Double は: the first marks 僕のおじいちゃん as the overall topic, the second (ふつうは) contrasts 'usually' with other situations ('but not always'). おじいちゃん is the affectionate form of 祖父 — used by family members for grandfathers in everyday speech. 朝食を食べる is a slightly formal way to describe eating breakfast; 朝ごはんを食べる would feel more colloquial and homey.