The score requirement varies on where and for what you are applying.
For applying masters programs in the USA, keep in mid that some universities might not accept the IELTS.
The score of 6 is roughly equivalent to a TOEFL score of 100-105... which is the intermediate category. in the end these scores are just cutoffs so a very high score doesnt help you much but I would still recommend retaking the test if possible to keep your options open
6.0 simply suggests that you are a moderate user of the language, you need to know how much score your course requires, some college for diploma programme even take 5.5 but thats rare. they atleast expect 6.5.