It's a nice word - but it's a skill most people would prefer not to need. Resilience is essentially the ability to keep going despite the odds being greatly stacked against you. The ability to "just keep going".

It's important to cultivate resilience when times aren't so bad, so that if situations get a bit more dire, you can still keep going without giving up - "sweat more in times of peace, bleed less in times of war", as George S Patton once said.