Read the law.

1) Companies should use belarusian hosters to provide online services in Belarus. Nothing special, just developing belarusian internet services.
2) When using public internet services such as internet cafe, you should show you passport. If you visit some extremist or terrorist sites, state wnat to catch you.
3) And for state factories and other state sites there are list of banned websites (porno, terrorist, etc.). Also nothing special.

That's all.

No restrictions for private services. I live in Belarus and use foreign services.