After enabling multilingual on website, you will see additional option to edit content in different languages.
Multilingual is controlled on field level, you need to enable it for each field that require multilingual.
First, go to content type editing page, click one field to open the field edit window.
Click "Advanced" tab, and check "Enable Multilingual", Click "Save" and continue to enable other fields.
Go to Text Content editing screen, you will see an "Multilingual" dropdown option on the top right corner.
Click on the option and check all the languages that you want to edit.
The fields that have multilingual enabled will have additional language related fields, see below screen.
HtmlBlock is very similar as Text Content, only that HtmlBlock has only one field and it is multilingual supported.
Go to the HtmlBlock editing page, check the languages you need, same as what we do at Text Content.
Label always has the multilingual editing open. Once you enable multilingual on website, the label editing window will automatically has all the languages enabled.
Go to Label list page, click "edit" to open the label editing screen.
On the label editing window, you can see all language values.