This is a YouTube video. What is this symbols means?
Let me google that for you...
Surface Texture & Machining Symbolshttp://www.m.mecanica.utcluj.ro/dt/curs/Engleza/surface_roughness_and_machining_symbols_full.pdfhttp://www.qualitymag.com/articles/84505-quality-101-surface-finish-measurement-basics
That is a Finish symbol defining the smoothness of the surface. The h7 is a hole fit up tolerance.
This may also help
Fits and Tol.pdf
The circle with two parallel diagonal lines is the GD&T symbol for cylindricity.
If you could give me the name of this symbols I can search in the YouTube and find further explanation.
As others have said.
1 , 2 = Surface Finish
3 = Hole Fit Tolerance
4 = GD&T (see screenshot below)
These sort of symbols are fundamental to creating and reading drawings. Given the nature of the questions, I would suggest Drafting or "Blue Print Reading" courses that cover the various topics of Fits, Tolerances, GD&T, Surface Finishes, etc.
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