expression
I assure you it is; it is, you know
Osaka dialect polite sentence-ending expression, equivalent to ですよ. Adds emphasis or assurance in a friendly, somewhat assertive tone.
See also: です
これ、めっちゃ美味いでっせ。
This is really delicious, I tell you.
明日は休みやから、ゆっくりできるでっせ。
Tomorrow's a day off, so we can relax, you know.