I ran 800metres in 5 minutes is that good?

Not for an adult but since you didn't tell us how old you are we really can't say.

age depends.... if you are like 8-11 yes.. over 14 not good

no its not. not even a sub 2:40.

a real good time is about a 2:03. or anything under 2. if your in high school, major colleges will start to look at you around 1:55