I have try to buy a domain .com but was taken , so i try to find some intel about it on whois but it say (on-hold (redemption period)) whats mean ?
It means that the domain has expired for more then 45 days and you have to wait another 30 days + 5 days to become available to register.
As Cheat said, you can't register the domain right now, but you can backorder it first. it's a safety precaution for preventing someone get this domain.
For your information, You can backorder in Enom for $69 or SnapNames for $59 They will charge you if only they manage to get you the domain name you want. Hope this information would help. =)
Or you can also wait some time not paying these fees. Not every free domain is taken over by someone.