Silk Test is going to be my automation tool. I have basic knowledge in selenium. But i don't know any frameworks. Instead of learning test4g which is Silk test's scripting language, can i directly learn silk4j?
Yes, of course!
Silk Test comes in four different "flavors", the Silk Test Classic programming language 4Test is just one of them. If you chose to go with Silk4J instead you still get all Silk Test features but can use the Java programming language. Since Silk Test 18.0 you can even use the Selenium API directly within Silk4J for web automation in case you prefer that to the "native" Silk Test API.
If you want to learn more about Silk4J you can get started with the free online course here as well: https://www.microfocus.com/ondemand/courses/silk4j-essentials-free/
Full disclosure: I’m the Product Owner for Silk Test and work for Micro Focus.