CRM stands for Customer Relationship Manager. A CRM is a piece of software that helps you manage your interactions with people outside of your organisation. As suggested in the name, CRMs were originally developed for use by sales teams to help them sell their products to customers more effectively, with Salesforce being the most famous of these. Since then, a whole host of other ways to make the most of CRMs have been found - as it turns out it's quite useful to keep track of how you're interacting with the outside world.
Charities often have a lot of people they aim to help and a workforce that is reliant on volunteers. This can cause a regular turnover in personnel, meaning that is easy to lose track of who has turned up to what event and makes it hard for one person to maintain consistent email contact with the person they are helping. CRMs are built to solve these problems.
Time to Spare is a CRM that has been designed specifically for charities, to help them solve the problems that charities face - it isn't a tool designed for sales people that has been repurposed for charities. This means that it works with the way you work, not against it. However, what is really special about Time to Spare are the reports it can generate, which are a great way to keep your funders informed of what you are doing, without filling out any forms.