Electronic – Capacitor Numbers, What do these markings mean

The brown capacitors have values in picoFarads

eg
47 = 47 picoFarad = 47 pF = 0.000 000 000 047 Farad !
10 = 10 pF

For the yellow and green capacitors with markings of the form

anb

Here n = nanoFarad = nF.

1n0 = 1.0 nF
2n2 = 2.2 nF
6n8 = 6.8 nF

Note that the use of xNx here is (probably) unqiue to capacitors in the nF range - I do not recall seeing eg xPx or xUx markings ever.

However page 70 of this superbVishay ceramic single layer capacitors document suggests you might expect to meet any of eg
p68 = 0.68 pF
n15 = 0.15nF = 150 pF
5p0 = 5 pF etc

The green dot is quite likely to be a voltage rating, but alas I don't know what system it uses. There are several different colour/voltage systems. Typically this sort of capacitor is 50 Volt rated but this is not certain.

More usual nnX 3 digit markings

Most capacitor numerical markings are 3 digit and express the value in pF (pico Farad = 10^-12 Farad) with the last digit being a power of 10 multiplier.

So

223 = 22,000 pF = 22 nF = 0.022 uF = 0.000 000 022 F
106 = 10 000 000 pF = 10 uF
100 = 10 pF and NOT 100 pF etc

Part of a larger tutorial series on capacitors. Deals in colour codes. Does not answer exact question but is useful

This does NOT answer the original question but is useful

I would say that these are indeed non-polarized caps. You would want to replace them with similar capacitors. Do NOT replace them with ceramic caps.

Ceramic caps are great for many purposes but not in the audio path. Among other problems, they suffer from piezo electric sensitivity and their value can vary greatly depending on the magnitude of the DC voltage across them.

Digikey and Mouser have suitable replacements available.