0dBfs is the maximum signal level a daw is capable of and all other measurements are rendered as some level below that value, which is why wee see all measurement as a negative number of dBfs
dB is never used on its own
it is used in relation to some nominal minimum value and some form of measurement unit for that value (in every other scheme this is the 0 level of that db in those units)
so we have dBu, dBm, dBv, dBV, dBVU, dBRMS, dBSPL
The Bel (originally a unit of sound pressure level (SPL)) is the ratio of some measured value to the nominal 0 value, expressed as a logarithm.
the decibel is 1/10th of a bel: i.e. 10dB=1B.
to get a sense of what the meaning of this ratio is, divide the dB value by 10 and then make it the exponent of 10; e.g 83dBSPL is the same as saying that something is 10[sup]83/10[/sup] (10[sup]8.3[/sup], almost 200 miliion) times as loud as the nominal 0dBSPL