Vtyjkyuk

I am trying to add a centrally aligned text in the middle of each horizontal bar, but can't seem to figure out how. How can I best do that?

 documentclassarticle

 usepackagexcolor
 usepackagetikz

 definecolorhighrgb0.89, 0.26, 0.2
 definecolormedrgb1.0, 0.65, 0.0
 definecolorlowrgb0.98, 0.93, 0.36

 begindocument
 beginfigure
 centering
 begintikzpicture
 foreach l/x/c[count=y] in A/6/high, B/4/med, C/2/low
 node[left] at (0,y) l;
 draw[fill=c] (0,y-.4) rectangle (x,y+.4);
 endtikzpicture
 endfigure
 enddocument

You just have to add a node at x/2:

documentclassarticle

% usepackagexcolor% TikZ already loads xcolor
usepackagetikz

definecolorhighrgb0.89, 0.26, 0.2
definecolormedrgb1.0, 0.65, 0.0
definecolorlowrgb0.98, 0.93, 0.36

begindocument
beginfigure
centering
begintikzpicture
foreach l/x/c/stuff[count=y] in %
 A/6/high/text for everyone!,
 B/4/med/more text,
 C/2/low/some text
%
 node [left] at (0,y) l;
 draw [fill=c] (0,y-.4) rectangle (x,y+.4);
 node [anchor=center] at (x/2,y) stuff;

endtikzpicture
endfigure
enddocument

Tikz defines a rectangle by two vertices of one of its diagonals, just place the node midway.

By adding a node in the middle of the path that traces the rectangle, we find exactly its center:

documentclass[tikz]standalone
begindocument
begintikzpicture
draw(0,0)rectangle(4,2)node[midway,blue]S;
draw[densely dotted, red](0,0)--(4,2);
draw[densely dotted,red](0,2)--(4,0);
endtikzpicture
enddocument

Your code becomes:

 documentclassarticle

 usepackagexcolor
 usepackagetikz

 definecolorhighrgb0.89, 0.26, 0.2
 definecolormedrgb1.0, 0.65, 0.0
 definecolorlowrgb0.98, 0.93, 0.36

 begindocument
 beginfigure
 centering
 begintikzpicture
 foreach l/x/c[count=y] in A/6/high, B/4/med, C/2/low
 node[left] at (0,y) l;
 draw[fill=c] (0,y-.4) rectangle (x,y+.4)node[midway]c;
 endtikzpicture
 endfigure
 enddocument

the result is:

Another way :

documentclassarticle

usepackagexcolor
usepackagetikz
usetikzlibrarypositioning

definecolorhighrgb0.89, 0.26, 0.2
definecolormedrgb1.0, 0.65, 0.0
definecolorlowrgb0.98, 0.93, 0.36

begindocument
beginfigure
 centering
 begintikzpicture
 foreach l/x/c[count=y] in A/6cm/high, B/4cm/med, C/2cm/low
 
 node[name=left-l] at (0,y) l;
 node[fill=c, minimum width=x, right=(.2cm of left-l)] at (0,y) c;
 
 endtikzpicture
 endfigure
enddocument

similarly to flav answer:

documentclassarticle
usepackagexcolor
usepackagetikz

definecolorhighrgb0.89, 0.26, 0.2
definecolormedrgb1.0, 0.65, 0.0
definecolorlowrgb0.98, 0.93, 0.36

begindocument
beginfigure
centering
begintikzpicture
foreach l/x/c/t [count=y] in A/6/high/tikz, B/4/med/love, C/2/low/I
node[draw,
 fill=c,
 label=left:l,
 text width=x cm,
 align=center, inner xsep=0pt, minimum height=8mm, right] 
 at (0,y) t;

endtikzpicture
endfigure
enddocument