A more thorough explanation:

A canonical impediment is a legal obstacle that prevents a person from entering into a valid marriage according to the laws of the Catholic Church. This can include factors such as a previous marriage that was not annulled, a close blood relationship, or a vow of celibacy.

For example, if a person was previously married and did not receive an annulment, they would be considered to have a canonical impediment to marrying someone else in the Catholic Church. Similarly, if two people were closely related, such as siblings or first cousins, they would also have a canonical impediment to marriage.

Canon lawyers, who are experts in canon law, are often consulted to determine if a canonical impediment exists in a particular case. They can help individuals navigate the complex rules and regulations of the Catholic Church to ensure that their marriage is valid.