I cannot download or update any applications

I presume you are referring to the "waiting" notice. Something is happening between your phone and Apple so you have a lot of testing to do. Or maybe just wait and see if it clears after a while.

At your end:

If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network - Apple Support.

https://support.apple.com/HT204051

At Apple's end:

https://www.apple.com/support/systemstatus

In between?

Sometimes restarting the phone will fix that. Give it a try. If that fails, put the phone in Airplane mode, restart the phone. Turn Airplane mode off and see if the download resumes. If that fails, try a forced restart.

No clue which iPhone model you have but you can find the forced restart instructions here.

If your iPhone, iPad, or iPod touch won't turn on or is frozen - Apple Support