Count the Number of process running for particular application

tasklist | find /I /C "appname.exe"

Example of Chrome.exe running in your Windows platform:

C:> tasklist | find /I /C "chrome.exe"
56

Example of chrome.exe running in windows:

C:\>tasklist /FI "IMAGENAME eq chrome.exe" | find /I /N "chrome.exe"
[4]chrome.exe                   17140 Console                    1    219,524 K
[5]chrome.exe                    4556 Console                    1      8,872 K
[6]chrome.exe                   14052 Console                    1    225,576 K
[7]chrome.exe                   13760 Console                    1     45,940 K
[8]chrome.exe                   16576 Console                    1     16,584 K
[9]chrome.exe                   12724 Console                    1     24,088 K
[10]chrome.exe                  17160 Console                    1     46,824 K
[11]chrome.exe                    244 Console                    1     50,592 K
[12]chrome.exe                  19268 Console                    1     45,132 K