Create an Excel Services service application - SharePoint 2013

a)   On the Central Administration home page

b)   Under Application Management

c)   Click Manage service applications.

d)   On the Manage Service Applications page

e)   Click New, and then click Excel Services Application.

f)    In the Name section, type a name for the service application in the text box.

g)   Select the Create new application pool option and type a name for the application pool in the text box.

h)   Select the Configurable option, and from the drop-down list, select the account that you created to run the application pool.

i)     Click OK