I was reading documentation about DXGI_SWAP_CHAIN_DESC and i came across with DXGI_SAMPLE_DESC
Count
Type: UINT
The number of multisamples per pixel.
now what exactly is multisamples per pixel?
DXGI_SAMPLE_DESC as you surmised is for specifying Multi-Sample Anti-Aliasing (MSAA).
That said, you should be aware that the SwapChain support for MSAA is not something you should use anymore. As such, just always set DXGI_SWAP_CHAIN_DESC.SampleDesc.Count = 1; and DXGI_SWAP_CHAIN_DESC.SampleDesc.Quality = 0;.
Instead, to use MSAA you should explicitly create your own MSAA render target and explicitly resolve the result yourself as part of your presentation of the results to the single-sample SwapChain. For details on why and how, see this blog post series.
Note that you can use MSAA SwapChains for DirectX 11 with the older DXGI_SWAP_EFFECT_DISCARD and DXGI_SWAP_EFFECT_SEQUENTIAL flip-effects, and the DirectX 11 runtime will do the resolve automatically. Per the blog post, this is NOT supported for DirectX 12 or the use of modern DXGI_SWAP_EFFECT_FLIP_DISCARD or DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL swap effects. This is really a 'toy' setup as any production rendering will do additional processing after the resolve from multi-sample to single-sample before putting it into the swapchain for display.
As you are likely new to DirectX 11, you may want to look at DirectX Tool Kit. I have a tutorial that covers MSAA.