I would like to learn SAP HCI & can you please suggest me sources to learn groovy script as well? Would SAP HCI as career is a good option? Kindly suggest.
Have you checked out the SAP Help Portal Learning Journeys? They provide a nice overview of a bunch of different topics. Here's the one for HCI, which is now known as SAP Cloud Platform Integration or Cloud Integration for short or CPI for even shorter.
There's also an openSAP course available. Be aware, though, that quite a lot has happened since the course was recorded. The fundamental concepts are the same, though.
As for the Groovy language, I'd start by browsing the documentation and resources available on the official website. Also, install Groovy on your machine and start experimenting.
Unfortunately, Cloud Integration is not available in the SAP Cloud Platform trial version. Early on it was possible to request access to a trial tenant, but I don't know if that is still an option.
Have fun with Cloud Integration!
On Addition to Morten's response you have a developers corner as-well.
Hope all this helps !!
thanks and regards,