How do you play Jax against Fiora?

Jax has the advantage with e. You either activate it as soon as you can for the stun, or wait for her .75 second parry to end to activate it

You can reactivate your e early or hold onto it longer which makes it hard for fiora to block it. Other than that standard way you play against fiora on any champion. Try to protect your vitals with walls

Try to sidestep her parry (when she uses it, step to the side and try to get behind her with your E up and ready to stun) and when she ults you, hug a wall so she can't hit all 4 vitals. Recommended items for dueling her are and you might consider taking or getting for her healing and lifesteal.

Early/mid game you should be able to beat her 1v1, but late game it can be close, since she also scales very well into late game.