A conditional is a relationship between two variables. So if I say 'If I'm wrong then I'll eat my hat' I am saying that I will eat my hat on the condition that I'm wrong. If I'm not wrong - then I don't have to eat my hat.

To say 'I'll unconditionally eat my hat' then I'm saying that I'll eat my hat quite independently of whatever else obtains (e.g., whether I'm wrong or not).

So... Unconditional love is (presumably) love that isn't dependent on anything. Typically the thought is that unconditional love isn't dependent on anything that the person who is the object of the love does.

Here is a question for you... Pick the person who you think might be the best candidate for your unconditional love. Now ask yourself whether your love for them would be altered (diminished lets say) if they did certain things. E.g., if they didn't love you back, if they came to positively hate you, if they went on to rape and murder and pillage, if they went on to aspire to the works of Hitler etc. If you would continue to love them despite their deeds then... Your love would be unconditional.

Is unconditional love something that we want to aspire to?

Perhaps. I think that love can come quite apart from the issue of accepting or condoning behavior. But... Do we love Hitler and co? Don't know...