Blocking immediately stops another member from contacting you or seeing your profile. You can block someone with or without reporting them.
How to block
From a chat: open the conversation, tap the three-dot menu (⋮) in the top-right, select Block (or Block & Report to also report them), and confirm.
From a profile: open the member's profile, tap the three-dot menu (⋮), select Block, and confirm.
When you block someone, they're removed from your matches and messages, and they aren't told they were blocked. See How do I report suspicious or inappropriate behavior? if you also want our team to review them.
Only use the block feature when you truly need to. Make sure you don't want to contact this person again before you block them, since blocking is permanent. If you'd simply like to skip a profile you're not interested in, tap the dismiss "x" on their profile instead — this removes the profile without you having to take the extra step of blocking.
Can you unblock a profile?
Unblocking is not possible. Once you block a member, the block is permanent and cannot be reversed — there's no way to undo it later. Before you block someone, make sure you don't want to contact them again.