I want to know the meaning of this sentence below my question:
question eligible for bounty in 2 days
Could you give me the right meaning of this sentence?
Bounties on Stack Exchange are a way to attract more attention to a question (for whatever reason); you can think of them as advertisements paid for with your own reputation.
The help center also mentions the following, which explains your question:
How do I start a bounty? When can I start a bounty?
A bounty can be started on a question two days after the question was asked.
The idea behind this is that in the first two days, a question should generate enough attention on its own, merely by being new.