Bom dia Ajay

First of all, I'd like to read the Outsystems documentation. it will give you all the information you need about the topic.

https://success.outsystems.com/documentation/11/reference/outsystems_language/logic/implementing_logic/logic_elements/client_action/?_gl=1*nm8ukq*_ga*MTEwMDc1ODY1OC4xNjgwMTU0NjMz*_ga_ZD4DTMHWR2*MTY5ODM4MzYzMi40Mi4xLjE2OTgzODM3OTYuMzcuMC4w

Hi Ajay Saminathan ,

Client action is  when u Executes an action that runs logic on the client side. It's available in reactive web and mobile apps only. Dragging the tool on the action flow will open the Select Action dialogue, for selecting an existing action or creating a new action. The action will be listed in Logic tab, under Client Actions. 

For more information you can refer outsystems Documentation

https://success.outsystems.com/documentation/11/reference/outsystems_language/logic/implementing_logic/logic_tools/run_client_action/

Hello @Ajay Saminathan 

Welcome to you on OS Community Forum!

For knowing more about Client Actions you can follow this videos tutorials-

https://www.youtube.com/watch?v=PtCp_bAGplE

OutSystem UI (Accessibility, Menu, Utilities)

https://www.youtube.com/watch?v=wRAxNmRaLPo&list=PLGZK5lgjWaJ0S3d9UVmE_hT2z-R3Qmw13

I hope these will help you.

Thanks 

Navneet Sharma