how to add a gap between clips in adobe premiere pro?
The closest thing in Premiere is the nudge keyboard shortcut. Select the clips you want to move and hit ⌘ / ctrl← or ⌘ / ctrl→ to nudge the clips one frame forward or back, and hold the shift key  ( ⌘ / ctrlshift← or ⌘ / ctrlshift→ ) to make it 5 frames. 

You can increase or decrease the amount it nudges in the preferences, so if you want ⌘ / ctrlshift← to nudge 5 seconds, open preferences then look for trim and change the Large Trim Offset amount to 125 (for 25fps, or 150 for 30fps).