For resize Multiple image in Photoshop

Follow the below steps

1. go to window menu in photoshop and select Action (or click alt+f9)
2. create new action by clicking below icon in photoshop

3. give any name to your action  press record
4. go to image size in image menu give any size you want
5. save and close image after that stop your action
6. now your action ready to perform multiple job
7. go to the file menu and select the automate and go to batch 
8. select any folder in source and press ok  

Trick-You can create action for any operation which you repeats every times