You are looking for the getbundlevalue(node, entry, field) function. Bundle nodes are characterized as having 'Entries' (rows) and 'Fields' (columns) of data and a zero based index of both. The zero based aspect can be a little confusing because the first row of data in the bundle is actually row 0.
So to use getbundlevalue(), you need a reference to the bundle node (like pictured above) for the first parameter, the entry number for the second parameter and the field name OR number for the third. For example if I had the following code:
treenode bundle = node("Tools/Experimenter/DashBoardData/Content vs Time/Scenario1/1/timedata", model());
double value = getbundlevalue(bundle, 5, 1);
My variable 'value' would get the number 17 because entry 5, field 1 is 17. Take note that the entry number is the number listed to the left of the square brackets [].