In chrome F12->network has a field with mywebsite.com name and blocking part of this field takes 30 second!
How can I reduce it?
This means the web browser is waiting for other requests to complete before issuing a new one. Your web browser is configured to have a maximum number of concurrent, or simultaneous, connections to a single domain. I'm using Firefox, and this maximum is 6 at a time. So only 6 simultaneous requests to www.knowarth.com can be active at a time. Different browsers have different limits.
Reducing blocking time is the reason why it is advised to reduce the overall number of requests your site makes by combining all your CSS and Javascript files into one single file. Doesn't affect the operation of the site, but can greatly reduce the number of requests and improve the load time.