Fiora Runes explained
There's one set of runes for Fiora on patch
11.7
that is the clear favorite for LoL players and pros alike. The best Fiora Runes on the position 
Top are Precision as the primary path and
Resolve as the secondary path with a pick rate of 26%. Besides runes you should take a look on Fiora Build and if you are interested in pro matches take a look at Fiora Probuilds. If you want to discuss
Fiora then you should visit the champion subreddit.
Primary path on Fiora
Precision improves attack and sustained damage on Fiora troughout the match. Most of high elo players – and our LoL pros in the the major regions – have agreed that
Grasp of the Undying is the best keystone rune to run on
Fiora. This keystone rune gives Fiora alot of sustain and helps to force your opposing champion out of the lane. This is usually followed up by taking
Triumph,
Legend: Alacrity and
Last Stand.
Triumph restores on Fiora a part of missing health and award bonus gold, if a champion is killed.
Legend: Alacrity grants additional attack speed to Fiora. With
Last Stand you deal more damage while you are at low health.
Secondary path on Fiora
When it comes to your secondary path, most
Fiora players prefer to go with
Resolve.
Resolve empowers the survivability of Fiora and increases the tankiness. On the
Resolve path, the best runes for Fiora are
Second Wind and
Bone Plating.
Second Wind powers up your sustainablity in lane by healing after taking damage from an enemy champion.
Bone Plating make Fiora overall tankier, by decreasing the amount of poke damage in the early game.