According to Exodus 25, six branches extended from the central shaft of the Tabernacle's lampstand.
The lampstand, or menorah, was made of pure hammered gold. Its central shaft had three branches on each side, producing six side branches and seven lamps in total. The design used almond-blossom cups, buds, and flowers as decorative elements.
A common mix-up is to answer seven, because seven is the total number of lamps or branches when the central shaft is included. The question asks only about the branches extending from the central shaft, so the answer is six.
The Tabernacle lampstand was not described as an ordinary household lamp. It was part of the sanctuary's sacred furnishings and was placed opposite the table for the bread of the Presence. Later Jewish menorah traditions draw on this biblical seven-lamp design, although the Temple menorah and the Tabernacle lampstand belong to different settings.