Propeller lets you keep track of the companies you deal with, which are called Accounts
the people at those companies, which are called Contacts:
and the deals you are working on or have won or lost, which are called Opportunities
Each opportunity has an amount, probability and close date, which help you forecast when revenue will come in.
Each opportunity is also associated with a Pipeline, which is the sequence of stages your deal goes through from start to finish.
Propeller lets you maintain multiple pipelines in case you have different types of sales or sales-like processes. For instance, if you want to track partnership and fundraising activities, you can use separate pipelines.
You can store data that is specific to your business using custom attributes.
Here are instructions for how to create custom attributes and add columns to a list.
You can also choose to enable the optional Leads feature to track unqualified deals/people/companies. Here's how to turn on the leads feature. Once you do it, you can see them here:
Leads also have pipelines and stages, similar to opportunities.
Your end goal for a lead is to qualify it and Convert it to an account, contact, and opportunity or to disqualify it and close it as Not Converted.
Here's how to convert a lead