I am testing a site using Burp Suite and stuck at a point. Is it okay to ask question regarding a features of tools like Burp Suite and other scanners ?
Questions about security tools are generally on-topic, as listed in the help center.
The burp-suite tag in particular is quite active with generally well-received questions. You should have good chances to get a quick response for questions related to Burp features.
Personally though, I'm not a big fan of questions about (commercial) security products: Many of them could have been asked without naming and advertising the specific security tool. That is, a lot of Burp questions are in fact just generic questions about HTTP interception proxies. Further, the dedicated customer support forums are sometimes a better fit for questions about commercial tools than SE.