普通、アマチュアでは250ヤード飛べばすごい飛距離だと言われます。

、。

Normally, for an amateur, driving 250 yards is considered an amazing distance.

Literal

Usually, amateur [at-では] 250-yards fly-[if-ば] amazing flight-distance [quotative-だと] is-said.

A golf-specific sentence. 飛距離 (flight distance) is the standard term for driving distance. ~ば sets up the conditional: 'if you can fly (the ball) 250 yards.' ~と言われます is the passive 'is said to be,' hedging the claim as received wisdom. ヤード (yard) is a loanword used in golf contexts.