formation red/blue arrows?

Hi ar all, i play top 11 on android when i go at the team formations and click at one player there cones a red arrow when i click second time there comes a blue arrow what it is , is the red arrow that the player play more offensive or is the red arrow that they work harder at a match sorry for my english

The red arrows moves them forward one position when attacking, the blue arrows moves them back one when defending. You can have one or the other, if red, he will maintain his position when defending, likewise for blue when attacking.