In neighbor discovery command, I am receiving only xmit, what does it mean?

It means your ldp neighbor router is not sending updates to you, where you are using sh mpls ldp discovery command.

Check your remote side neighbor configurations, whether Mpls is configured on interfaces or not using sh mpls interfaces

Then Check global command of mpls ip and ip cef and ldp update source as well.

You can see only xmit in neighbor discovery command which means neighboring router isn't sending any ldp hello packets. You can check on neighboring router whether MPLS enabled or not.