plural noun or singular

Hello,

Could you tell me if this sentence is correct if I mean that Jim and Ann are two friends of mine, two different people, i.e. not siblings ora couple.

Jim and Ann have got a car.

Thank you,
heyt

Your sentence means that Jim and Ann have a car which they share and own jointly, even though they are not siblings or a couple.

Perhaps you mean 'Jim and Ann each have a car'.

That means Jim has a car and Ann has different car.

Rover

Thank you, I see.

What abou this sentence:

Jim and Ann both have a car.

Jim and Ann have got a car. If you pronounce the 'and' forcefully, in a high tone, then you have said the same as:
Jim and Ann both have a car. They each own a car.

'Jim and Ann have got a car.' is a bit ambiguous, with possible meanings:

Jim and Ann together have a car. They share the car.(one car)
Jim and Ann each have a car. They each have a car. (two cars)
Jim and Ann together have recently aquired a car. (one car)
Jim and Ann have both recently aquired a car. (two cars)

What a lot of meanings!