To push source to scratch Org, run the following command:

sfdx force:source:push

For our use case, we can change the HelloWorld.cmp file code, as shown in the following screenshot:

Once you run:

sfdx force:push

the code is deployed to the scratch Org. The screenshot shows the command-line interface once the code has been deployed successfully:

Also, note that you can always find the status change between your local folder and scratch Org using the following command:

sfdx force:source:status