Microsoft re-brand Office 365 K1 as Office 365 F1. Previously the “K” was for “Kiosk” – those workers who typically use a PC for less than 10% of their time. “F” is for “Firstline” where firstline workers are those who are the first in line to engage with customers in the manufacturing, retail, healthcare, government, and many other sectors. Currently the F1 plan gives access to the same services as K1.
Check out this page to see what F1 includes and for a couple of useful FAQs: http://bit.ly/2uwemPH.