Google Drive
You can use a G-Drive url to load data in. Here are some quick steps to getting your data into a colab notebook.
Click the little folder to open up your file system for the notebook.
Click the folder with the logo to Mount the Drive
Use the dropdown to copy the path for the data you want to use.
Load the file into a notebook and plot the data
Session Storage
Another method is to use the session storage. You can simply upload a file to the colab enivronment using the file upload button. It's quick and easy, but it will delete the file after you close the session, meaning you have to do it again if you take a break and restart the colab notebook. (And your code won't work for anyone else, since they don't have the file anymore.)
Use the file upload to load a file into the session.
Use the same copy path for this file too.
From the Web
You can also just grab data from many different resources online. Here's an example that grabs a csv file from the NYC OpenData portal: https://data.cityofnewyork.us/Environment/Water-Consumption-in-the-City-of-New-York/ia2d-e54m/data
Water Consumption in NYC over time.