What does TVL-E13/2 mean? I know that the TVL system exists but I am not sure if TVL-E13/2 would mean it is 50% of TVL-E13 or what does the &quot;/2&quot; mean, could someone explain please? I've seen it in multiple PhD positions offers.
A good source of information regarding TV-L is the TV-L calculator at https://oeffentlicher-dienst.info/c/t/rechner/tv-l/west?id=tv-l-202, which is supported by current TV-L employees (but not actually official).
The calculator has the following main options (from top to bottom):

TV-L level, e.g. E13
TV-L stage (with increasing work experience, you get more money)
Percentage of a full position

The other options are useful to compute salary after taxes (taking pensions and healthcare costs into account), but are set to reasonable defaults.
After choosing options, click the gray &quot;berechnen&quot; button. The number marked in bold in the left column will be the exact salary before taxes, the bold number in the right row the salary estimation after taxes.
EDIT [Updated answer]: Regarding your specific question: /2 appears to most often refer to the percentage by which the position is funded, as you proposed. However there appears to be some ambiguity around this. Does the main body of these  adverts you're looking at contain more specific information?