YouTube Channel: 3Blue1Brown
Host: Grant Sanderson
This YouTube channel is a great resource to gain a basic understanding of linear algebra and calculus. There is a series of videos for each topic of amazing videos that will get you started and make it easier to go deeper in either subject.
The Essence of Linear Algebra series, a popular one, contains 15 videos. The subject ranges from vectors to determinants to dot products with video length going from five to fifteen minutes. Watch this if you’re starting your linear algebra journey to get the concepts down.
The Essence of Calculus series has 12 videos and focuses on derivatives. It starts with the basics, moves onto the chain rule, and then mentions integration. I recommend that you watch this just before starting Calculus 1.
There are other series and playlists on such topics as neural networks, differential equations, geometry, and physics. Each one is of high quality and useful when you want to learn about those topics as a beginner.
I would personally advise you to watch these two series just before starting a course or working through a math book on your own. They will help you understand the overall concepts and give you a solid foundation. They can also be useful if you need a refresher before taking a more advanced course. These do not substitute learning about the topics in detail.