What will resetting your network on your iPhone do?

Will it only log you out of your Wi-Fi? Does it log you out of anything else, like apps? And does it delete anything?

It will just log out of Wi-Fi, nothing is deleted as far as I know.

You would lose any access to Wi-Fi connections you have used in the past. Those with passwords would have to be re-entered to be used again. Could also reset the APN settings for data use on a carrier network.

No it wouldn't affect app log-ins nor would it delete anything.