Hi @mhatreuduyu, welcome to Thunkable! 
Be sure to check out our posts about How to ask Great Questions v2.0 and our Community Guidelines as you get started.
We need some more information to be able to help you. Have you tried setting this API call up yet? Blynk does have documentation for its API:
I don’t know about this platform but the URL for accessing Multiple Datastream Values is:
https://{server_address}/external/api/get?token={token}&{pin}&{pinX}
So you would need to have the server address, token, and PINs. Are those things you have access to?
If so, you should be able to set the URL using our Web API component
https://docs.thunkable.com/blocks/advanced-app-features/web-api#adding-a-web-api-to-your-app
Let us know what you have tried so far, the response you are getting, and we can help out from there! 