Mechanic Question!

I know this may be a dumb question, but I don't know the answer... There is a truck in Maine for sale that I want to buy and drive back to NY. The truck looks pretty mint but the owner said that the #1 and #5 cylinder have low compression... My question is,

1)what does that mean?

2)How bad of a problem is that?

3)What are the possible reasons for that?

4)How Expensive is it to fix?

5)Will the truck damage if driven, and if no, how long could you drive it?

6)Most of all, how severe is the prob????

Please HELPPPPPPPP!!!!!!

it means that the rings (most liekly) are worn. if not the rings then they cylinder wall its self. depending on how low they are is how much of a problem it is. how expensive to fix? depends on what kind of truck.. call a local shop and ask for prices to re-ring. Damaged if driven..?? depends on how bad it is.. probably be o.k...... but very hard to say! think about the forces happening on the crank as 6 pistons to their thing, and 2 are just mushing along,, Is a motor rebuild severe to you? depends on how much you like the truck, and what kind of a deal you get. Its basicly heart sergery,, and then you have to ask your self " what else to i change/fix while the block is being worked on.. should i do the heads, water pump, bla bla bla".. hope this helps............