We from this we can start with the Wikipedia explanation of what SharePoint is:
Microsoft SharePoint, also known as Microsoft SharePoint Products and Technologies, is a collection of products and software elements that includes, among a growing selection of components, web browser based collaboration functions, process management modules, search modules and a document-management platform. SharePoint can be used to host web sites that access shared workspaces, information stores and documents, as well as host defined applications such as wikis and blogs. All users can manipulate proprietary controls called “web parts” or interact with pieces of content such as lists and document libraries.
In this brief explanation you might scratch your head and say ‘well that really doesn’t tell me much’. What SharePoint is at it’s core is a platform from which you can stack and build tools that can used to suit your needs. Do you need a simple site that your team collaborate with word documents, keep a unified team schedule, and make company announcements? Or do you need to web site where your internal team can coordinate times and resources with outside vendors/suppliers? Do you need an Internet facing site where resources are available to people who need the information? SharePoint can do all of these things and more. Consider the Orange County School Public Schools entire Internet facing site is SharePoint. At the core SharePoint is a sharing platform. It wants to share information. Is it always the best? Honestly, not all the time. Consider if you only wanted to blog. Well in that case something like WordPress would be much stronger blogging platform, but it is only a blogging platform. That is its primary but only strength. With SharePoint you can blog, share calendars, have document collaboration, Excel services, Employee Self-Service Benefits, New Store Opening, IT Team Workspace, Event Planning, etc, etc… Try doing any of these with WordPress. A better question for you is what are my current business needs.
Don’t just drop SharePoint in and expect everything to be fixed. Look at your needs and see if SharePoint can be used to make work-flows easier for you and your team. As an example when you are trying to coordinate an event do you email a single excel document at eventually turns into 2, 3, 10 copies, where you don’t know who has the real copy? SharePoint with a shared document center can centralize that process where there is only one copy and you can see whom and when changes were made, and have it integrated with your existing Active Directory structure. I don’t know what exactly you need so take a look at some great Microsoft demo videos.