Step by Step Root Guide :
1) First Download J7 Nxt root file from below given link and Extract it,
2) Copy Supersu.zip file to your internal storage/ SD card,
3) Now Go to Settings -> About Device ->Software Information and tap Build Number for more than 8 times until it says Developer Options is enabled,
4) Go back and find Developer options and enable OEM Unlock and USB debugging,(Enabling OEM unlock is very important.)
5) Now turn off your Samsung galaxy SM-J701F and press and hold the Volume Down + Home + Power keys at the same time for 2-3 seconds to boot your phone into the Download mode,
6) Release the keys as soon as you see a blue screen with exclamation sign and press the Volume Up key,
7) When your phone gets into the Download/ Odin mode, connect your Galaxy SM-J701F to your computer using a USB cable,
8) Open the Odin folder and launch the Odin v3.xxx as administrator,
9) The ID:COM port on Odin will be highlighted in blue/ yellow as soon as your device is detected,
10) Click the AP button in Odin and add the twrp-xxx file which you have downloaded,
11) Then Click the Options tab in Odin and uncheck Auto-Reboot option.
12) Now click the Start button to start TWRP installation. When TWRP is installed and you get PASS! message in Odin. Disconnect the USB cable.
13) Now press and hold the Volume Down + Home + Power buttons at the same time and immediately swap to Volume Up as soon as the screen goes blank/black while still pressing the Home and Power keys.
14) Keep the 3 keys pressed until you get into TWRP Recovery.
15) At this point, you will reach the screen asking if you want to allow system modifications. Swipe for modification.
16) Go to install and select supersu.zip file. Swipe again to install Supersu file.
17) After the SuperSU.zip is flashed, go back to TWRP main menu and tap Reboot System.
18) That's all,first boot might take a few minutes so be patient and your device may restart several times
19) After that your phone start normally and you can see a Supersu Apps,
20) You can check your device rooted or not by using root checker apps from playstore.
(Rooting a device void your warrenty so do it at your own risk, after root you can use a custom/ modify OS on your phones).
Note: After root if your phone didn't start well or it stucks on bootloop then flash with “J701FDDU1AQF8" file and root again.