help getting email on my Mac

The "sideways s" indicates that Mail is having problems connecting to that account, so that is consistent with the mail messages not showing.

Sometimes, clicking on that "sideways s" eventually brings the account back to life; also you may try to do

Mailbox->Bring All Accounts Online.

Did you use to get mail to your mac, and this just start to happen recently? Any recent change that might account for it?

If you can't send or receive email on your Mac - Apple Support has a number of suggestions. For example,

"You might see a status icon such as a lightning bolt or warning symbol next to your account's inbox in the Mail sidebar, or in the upper-right corner of the Mail window. Click it to learn more."

Not much to be getting on with... what type of account (iCloud? other IMAP?); what application are you using for e-mail on the mac (Apple Mail? something else?).

What happens when you check for mail? Any mark next to your account in Mail sidebar (if it is Mail)?