It refers to UTM (Universal Transverse Mercator) zone 19, using the WGS 84 Datum (earth modelling system). The " sign after 19 in the question is a closing quotation mark, I take it, not the sign for seconds, which would not make sense with "huso".

The UTM coordinate system divides the earth's surface into 60 zones, each with a width of 6º of longitude. The reference should really give N or S (north or south) after the figure 19.

These zones are not to be confused with time zones (husos horarios); they are quite different, though "huso" still means a zone. The word really means a segment of the surfact of a sphere.

"The UTM system divides the Earth between 80°S and 84°N latitude into 60 zones, each 6° of longitude in width."
https://en.wikipedia.org/wiki/Universal_Transverse_Mercator_...

"Se divide la Tierra en 60 husos de 6º de longitud"
https://es.wikipedia.org/wiki/Sistema_de_coordenadas_univers...

"Figure 2-14 The UTM zones, numbered 1-60. [...]
More recent UTM maps and GIS data sets, however, tend to use WGS84, and this is the choice of the Landsat images available on the GCLF website (http://glcf.umiacs.umd.edu/data/)."
https://www.rgs.org/NR/rdonlyres/CD054AD2-18FB-47BA-B112-494... (p. 15)

"You are also responsible for taking a GPS location (WGS 84 datum, zone 17) of the sample."
http://geology.wlu.edu/connors/Geo250/Rock_Deformaton_Lab.ht...

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Note added at 49 mins (2015-11-09 13:49:18 GMT)
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The reference would have been if "UTM" had been added before "huso", though it is often omitted.

"WGS 84 / UTM zone 33N"
http://spatialreference.org/ref/epsg/wgs-84-utm-zone-33n/

"It was projected into a UTM coordinate system with spheroid WGS 84 and datum WGS 84 (zone 39)."
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=430220...


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Note added at 50 mins (2015-11-09 13:50:40 GMT)
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I meant to say "the reference would have been clearer/more complete" in the first line of the added note.