Translation:My grandfather can speak English.
会 implies can/is able to/know how to. Your sentence would be translated as 我爷爷说英语
I think the normal interpretation of the English sentence "My grandfather speaks English" is that is can/knows how to speak English.
It would be different in the sentence "My grandpa is speaking English." 我爷爷在说英语 (hope this is correct grammar)
Correct. He speaks English=he has the ability (he can speak). He is speaking English=he's talking now and using English. In this sentence can is optional and the meaning is essentially identical.
In english, "My grandfather speaks English." means "My grandfather know how to speak English". so it is definitely more proper. Can speak is more for 我爷爷可以说英语。
This is "paternal grandfather." In our family, everybody has a different title, with aunts and uncles etc. assigned names and numbers depending on whether they are on the husband's father's side, wife's father's side etc.
Yet "my paternal grandfather can speak English" wasn't accepted. Reported.