As I know on page only need to put 1 H1 tag, but how about H2? only 2 times? or I can use it 5 times? or better for that H5? Just woried, not to hurt my seo rankings.
H1 only once The others, as many times as you want/need just make sure you use them correctly - i.e. NOT JUST FOR SEO REASONS! heading tags are for telling screen readers where headings are and for assisting search spiders to read the pages properly.
You can use h1 at once only for content. h1, h2 are the a seo technique we can also called "Content optimization".
The way I see it, you could only use one H1 H2 I've only really used 2 or 3 times maximum. Ive been using H3 for everything else in content a number of times. H4 - H6 Use these only really for side navigation or footer headers. Its literally content importance ranking so which ever is the most important should have the lower number
Depends on how to want display if you want to heading 5 then you could use or use it font-size 5 also