You can use the 4-way splitter to divide the signal output from your repeater and feed up to four indoor coverage antennas. You can purchase additional cables to connect your indoor antennas.
The most popular style of indoor coverage antennas for applications with splitters are the omni-directional celiing mount antennas, which can be found here. Installation involves connecting the splitter with a short cable lead to the input of the splitter. The four outputs connect with cable to the indoor coverage antennas.