A cultural round or cultural rounds may be a round-robin style approach a company takes for you to talk to various team members in a more casual behavioral interview.

What I mean by that is say you're interviewing for a design role. You might have a round-robin culture round with a designer, and/or a researcher following your portfolio round.

Conversations for this round is rather casual in nature but might run through those you'd face in a phone screen that asks you about the interest in a company, getting to know a person on the team, and ask questions about how they operate UX and a better way to know you as well in terms of what you bring to the table.