This page of the Final Fantasy 7 Remake guide contains a description of the fight against Reno. You encounter this opponent at the beginning of Chapter 8 - Budding Bodyguard.
Reno isn't very challenging. First, you have to defeat a bunch of minor enemies. Reno attacks primarily with his baton and is extremely vulnerable to Punisher Mode counterattacks. Just watch out for his Shock Swipe attacks - he can quickly shorten the distance and shock you.
The sword quickly builds up Pressured and Staggered statuses, so focus mainly on melee attacks. When the enemy hurts you, use Regen and Cura. After taking half of his HP, you will begin the second phase. This time, Reno starts throwing EM Mines, which deal damage and stun you. Use Triple Slash and destroy mines as fast as possible. Then focus your attacks on Reno - watch out for his attacks and counter him.
Reward: 600 EXP, 10 AP, 600 Gil, Bottle of Ether.