Tifa is a free unit obtainable during the Final Fantasy 7 Remake collaboration. She's a Wind bruiser type unit with a simple play style of "get close and punch hard", but she does her job quite well at being a hard hitter without needing to use many skills to ramp up.
In PvP, her role is a frontliner that excels at picking off units one at a time. Overpower+ is a pretty good opener because of the mobility, range, and debuff. Once close, she can use her empowered Omnistrike for some one punch kills, or use Limit Burst for a mid chance to 2 turn stun an enemy. She has decent survivability too depending on which sub-job you run her with, and if you raised her AGI and Luck stat for some evasion. Monk (FFVIIR) sub-job has a "guts" type buff, while Paladin has Sentinel and Saintly Wall.
She also synergizes quite well with 2B, a previous limited-time collaboration unit. Both have stats good for evasion, and 2B can use some strike attacks which means that she can chain with Tifa and benefits from Tifa's VC + TMR, making the two of them quite a killer combo.
If you're wondering whether or not she's worth raising, then the answer is yes, especially if you intend to get serious with PvP. Definitely a no-brainer if you have 2B and Nier: Automata VC. Even better if you managed to get Tifa's VC when summoning for Cloud. But if you're low on visiores, then consider looking at future units and see if there are any that fits your team/element better.