Hi,
What can be done is creating a custom field via the menu Display > Custom fields.
Then select the table "order" to display it in the checkout (or "item" to have it on a product page), for the type select "checkbox" and set a value for this text box.
To put a link in the text, you have to set a value like "CUSTOM_TERMS_AND_CONDITIONS" then in Configuration > Languages add an override to display the desired text, like:
CUSTOM_TERMS_AND_CONDITIONS="My terms and conditions <a href='yourcustomlink'>here</a>"