How to skip aut0 login page and directly redirect in to social login site?

what will return “getTokenSilently()”

You can check the API docs here:

https://auth0.github.io/auth0-spa-js/classes/auth0client.html#gettokensilently

If there’s a valid token stored, return it. Otherwise, opens an iframe with the /authorize URL using the parameters provided as arguments. Random and secure state and nonce parameters will be auto-generated. If the response is successful, results will be valid according to their expiration times.

actuvally i am getting something like"21h3SAHv0oLqTevhxPAL91muyfj9SE" .

This looks like an access token in opaque string format, not JWT. This is because you didn’t define the audience (that should be the API identifier of your API registered in Auth0 under Dashboard > APIs) in the request. See https://auth0.github.io/auth0-spa-js/interfaces/gettokensilentlyoptions.html#audience

Something like:

const token = await client.getTokenSilently({audience: 'https://example-api/}); . // replace with your own proper API identifier