Hello Dinesh V,
The Host name is the endpoint of your Shopify server.
ex: mystore.myshopify.com
To get an Access Token, it depends on the type of app you are creating. If you are creating a public app, which can be installed by any Shopify store owner, you need to use OAuth to authenticate your app and generate an Access Token. If you are creating a private app, which is only for your own store, you can create an Access Token from the Shopify admin.
Please see the below document from Shopify:
How to Generate a Shopify Access Token
https://www.shopify.com/partners/blog/17056443-how-to-generate-a-shopify-api-token
Shopify API authentication:
https://shopify.dev/docs/api/usage/authentication
I hope this answers your question.
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