Walz is from Minnesota. Minnesota is in the Midwest. Some people in the Midwest have a unique and rather quaint dialect and accent, as well as a very friendly culture.

“'Ope” is an exclamation akin to “Oops”, and is often said when a Midwesterner may have accidentally bothered someone in some way (e.g. bumping into them accidentally).

This exlamation is often followed up by “sorry boutcha” to form the iconic phrase: “Ope! Sorry boutcha!” Which is basically the folksy, Midwestern equivalent of “I beg your pardon”.

Ope has beocme an iconic, memetic symbol of Midwestern identity, culture, and stereotypical friendliness.

This might help.

https://youtu.be/qb_-taYLRfY