-Before doing anything you have to backup your Samsung Galaxy S5 Data See this guide here
1-You need to enable USB debugging mode which is deactivated by default. (you can skip it ) 2-Your S5 should have 70-80% charge remaining.
3-USB Cable to connect your phone with your PC .
Downloads :
Step By Step Root For Galaxy S5 :
1-Download and install OneClickRoot App
2-Follow app instructions
3-Wait until it's done and phone will restart