Electronic – What does “NS” indicate as a capacitor value

First of all, this is a nonstandard and unhelpful way of calling out component values. Don't do this on schematics you draw! (In normal practice, "R220" means "resistor number 220" and the value is shown separately.)

But somebody with experience might be able to figure it what's going on. Let's see how I do...

C180 must mean 18 pF. Those are crystal load capacitors, which are commonly in the 10 pF - 20 pF range.

C105 means 1 uF. These are bypass capacitors and 1 uF is a common value and the datasheet-recommended value.

R220 probably means 22 ohms, from the example circuits in the 32u2 datasheet.

I found this drawing in the datasheet:

Also notice the supply connections. The micro has its own internal regulator, so the Vcc doesn't need to be connected to anything else (except its bypass capacitor.)

None of the components are super critical. 10% tolerance should be fine.

Once again, don't use this as example of how to draw schematics.

(edited to revise 0.1uF guess to 1 uF.)

It's a fixed current source (DIN 40700 style). With an arrow pointing to it an externally controlled current source. In this case it's a CCCS (Current Controlled Current Source), where the generated current is the controlling current divided by 500, resp. 1000, depending on the device.

Other common current source symbols include:

Controlled current sources may be indicated by:

or