After so many years of slow system, AT&T is providing us some new services and better connection on the internet. the issue that I am having that when they come to connect our new systems I will be receiving new Static IP addresses from AT&T, so I am not sure what changes I need done to have our server working properly.

I am trying to get information if I have to change information on my MX records or another type of information.

I am very new on the Exchange server system (we have 2013).any information will be useful

thank you

You're on the right path.  Since AT&T will assign you new static IPs, there's the obvious changing of old for new on your firewall(s).  Whatever new IP you choose for email communication, once changed on your firewall you'll change your DNS "A" and "MX" records for email delivery.  If you're currently using a SPF/TXT record, that too will need to be updated as well as any PTR records in use.

I'll add there is very little if anything to change on the exchange it's mostly DNS and firewall changes primary external, ATT will have to create a reverse dns record for you too on their end.

MX record is how email gets to you, it may go to your exchange server or to a standalone spam server or service filter.

Reverse DNS is one way other email servers verify it's you sending the email, it takes the ip address the email arrived from and see's if it has a matching domain associated with it. This is a attempt to verify that it's your server the emails is arriving from.