The "Labels/Refs" tabsheet will show all the labels used in your TeX project (labels are commands specified by LabelsMarks parameter). Labels are used for (cross-) referencing, so also all the references of a label are given (the parameter RefMarks). Using this tree it is easy to see which labels are used and whether these labels have a reference somewhere in your document. If not, you could delete the label. You can also see which references do not have a label (i.e. shown under the label !!!References without any label!!!). These references can contain typo's or a reference to deleted labels. Correct the errors, otherwise you will have empty references that show up as question marks in your document. Note that all the labels and references contain the filename and line number of the label/reference (between brackets). By clicking on the label or reference the editor with the correct filename is opened and the editor jumps to the correct line number.