Both in Bitrix24 Activity Stream & My Requests section under Workflows you can find several pre-made Workflows templates. After these workflows are launched by your colleagues, you may be one of the users who need to approve on them - that can be done in your Activity Stream or in Workflows section under My Workspace.
Please note that business processes\workflows are available for Bitrix24 Standard & Professional plans only.
In Workflows users will find those assignments which require their reaction. The counter next to the Workflows section will advise if there is an amount of processes addresses to you:
If you have several Workflows addressed to you – you can perform group actions on them: tick several Workflows and choose group action:
For example, if you are going to a business trip or vacation, you can assign your current workflows to another user: