Capacitor marking with line underneath; these aren't tantalum (I don't think anyway), so I'm not sure which units the capacitance is written in.
That is a ceramic disc capacitor, 47 pF.
Here's a datasheet for a typical capacitor of this type:
A good clue: The two capacitors, crystal, and resistor appear to be an oscillator circuit, perhaps for the IC next to them; in this use the capacitors are almost always a few 10s of pF.
This circuit is from ST's excellent oscillator design guide for these AN 2867
Encoding for Ceramic Capacitors
Ceramic capacitors encoding consists 1-3 digits.
If the capacitor code consist only 1 or 2 digits, it is simply their capacitance value in PicoFarads (pF). For example if a ceramic capacitor has a code ‘5’ and other has ‘47’, their respective capacitance values are 5 pF and 47 pF.
That is a ceramic disc capacitor, normally you would have three figures on it, and the value is in pF; 470 means 47 x 10^0 = 47 pF, 102 = 10 x 10^2 = 100 pF and so on.
I suppose in this case they just omitted the 0 for some reason.
Rest assured it is not a 47 µF capacitor