CD4017BE is a 5-stage Johnson counter and has 10 outputs. Output Q0-Q9 counts according to the pulses applied to Clock, Clock inhibit and Reset inputs. By connecting the Carry Out output to other CD4017BE ICs, you can create a cascade connection.
As can be seen in the timing diagram, if the Clock Inhibit (Pin 13) and Reset (Pin 15) input pins are in the logic 0 state, the decoded outputs is activated in sequence if the clock pulses are applied to the Clock input (Pin 14)
When applying clock pulses to the Clock input, if the Clock Inhibit input change to logic 1, the counter stops counting. Similarly, if the Reset input changes to logic 1, the counter is reset and the outputs are cleared.
The 4017 ic has a Carry Out output so you can make more than 1 connection. For example, you can create a 0-99 counter circuit by connecting the Carry out output of the first 4017 counter to the Clock input of the second 4017 counter. Thus, when the first counter becomes 10, it is reset and the 2nd counter increases by 1.