Dispensation in the Catholic Church means getting permission or allowance to do something that is not normally allowed according to the Church's rules.
For instance, getting married outside the Church or having meat on a day when it is otherwise prohibited are examples of things that might require a dispensation.
It's like getting a "special pass" to do something that is usually not allowed, but only for specific reasons and with permission from a higher authority.
Dispensations might be given by a bishop or the Pope himself, and they are usually granted only in exceptional circumstances. It's important to obtain dispensations properly before doing something against the Church's laws, to avoid committing a sin.