Ubuntu has its own comprehensive list of fonts that you can use. But if you are making a switch from Windows or Mac to Ubuntu you would like to use the fonts you have been using for a long time. Even widely used fonts such as Arial and Times New Roman might not be available in your Ubuntu distribution. You cannot directly install your existing Windows and Mac fonts in Ubuntu, but there is obviously a workaround.
This blog post on Make Use of explains to you step by step, how to install and use your existing Windows and Mac fonts in Ubuntu.