I have a visual Brand on the category Axis and net measure on the value axis. I would like to add the city column on the tooltip, but there are multiple cities, how can I show all city values on the tooltip?

You can create a measure that provides concatenated values and then add this measure to the tooltip option of the visual.

Cities = CONCATENATEX(values(Geography[City]), Geography[city], ", ",Geography[City])

Using this expression, we will concatenate the distinct values from the ‘city’ column in the ‘Geography’ table, separating them with a comma and a space, while sorting them alphabetically.