my current page is /items but after clicking the link it moves to items/checkout/1 instead of checkout/1 [duplicate]

I'm using this link in my current page but whenever I click the link it moves to a different path. It appends the below url to my current url

Buy Now

For ex above link when clicked should go to /checkout/1 and my current page is /items but after clicking the link it moves to items/checkout/1 instead of checkout/1

How can I solve this problem?