How can a developer upgrade a Magento 2 store to the latest version?

git pull
composer self-update
composer update --prefer-source
bin/magento setup:upgrade

Thanks For consideration Dmitry but ,

These commands to run in ssh and how to run
"git pull" command and what does this command do.

composer self-update

composer update --prefer-source

bin/magento setup:upgrade

https://www.google.com/search?q=git+pull

See also:

Connect to your web server via SSH. Log in to your Magento 2 server with full file system ownership.

Navigate to your Magento 2 ROOT directory.

Enter

composer require magento/product-community-edition 2.1.3 --no-update

If you want to later upgrade to future version, when they come out, you can change 2.1.3 to that version number.

composer update