HOW CAN WE SAY THAT EUCLID'S 5th POSTULATE GIVES AN IDEA OFnPARALLEL LINES

Yes.

According to Euclid’s 5^th postulate, when n line falls on l andm and if

, producing line l and m further will meet in the side of ∠1 and ∠2 which is less than

If

The lines l andm neither meet at the side of ∠1 and ∠2 nor at the side of ∠3 and ∠4. This means that the lines l and m will never intersect each other. Therefore, it can be said that the lines are parallel.