No. It's not about being a know-it-all, that's just annoying.

Mansplaining is a bilateral interaction. It's not just about what the man does. It's about how the woman falls into a particular pattern of behavior, 'the ingenue' and then later feels aggravated and put up on (for lack of a better term) by the man and either angry at herself for "falling for it" or disappointed in herself that she didn't set him straight/defend her integrity in the moment.

She was the expert.

If you want to understand mansplaining in a full sense, I recommend you read Rebecca Solnit's essay "Men Explain Things To Me". It's free on Kindle Unlimited and several other places. It's humorous and examines the whole dynamic.

It does not bash men.

Still, it's no secret that men walk around the worls with assumed expertise they don't always have and turn to that confidence they have about their capabilities to cover social awkwardness or anxiety. Or to try to impress.

Ultimately, that's what mansplaining is.

As you can see, not the same as being a know-it-all.

I didn't read the Wiki article on it, and I recognize that the term has shifted somewhat since it's initial inception, but I'm guessing you just pulled out one statement of a broader section and went with that.