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This means that your Jira is running on https, and your browser is not able to negotiate the right secure connection configuration with it.
(This is vastly over-simplified to try to keep it simple for us human end-users, before any SSL experts leap in)
What happens with most secure (https) sites is a browser hits them, and asks "how do we encrypt our conversation?". The server then hands back a token or certificate that the browser can use to encrypt what it is sending, and decrypt what the server is sending back. A lot of other client types can handle that too, it's not just browsers (wget, curl, etc).
But, if that goes wrong for some reason, then you'll get the error you are seeing. You might need an additional certificate, you might have a mis-configured server, or you might have a browser that doesn't work correctly with the protocols the site is demanding you use.
Quick test - try it in another browser. Do you get a similar SSL error?
Either way, you're going to need to talk to the admins of your Jira system to find out what is wrong and how to get into it.
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