A multirest (multi bar rest) consists of a rest sign for a whole number of measures: with a number to indicate the number of measures. Each measure has the duration as stated in the time signature. The numbers in multirests use a separate text type. The design and position of that digit can be done under [Options|Layout] for rest numbers. The automatic bar numbering is adjusted to the specified number of rest measures.
Please note, a multi rest is shown in score view with the correct number of single bar rests. On the notation bar you can recognize a written multirest by a staccatissimo characters at the rest, indicating that it is not an 'ordinary' rest and a dark gray number above it.
You can use the tool 'multirest expansion' to permanently replace a previously inserted multi-rest with a corresponding number of regular rests.