Yes you can!
Your email address can only be used to create one account. However, your email address can be invited as owner/user for multiple accounts. This needs to be done by another owner user (i.e. the email address that created the account). For more information on user roles and the invitation process, see this article.
Note: user access applies to the entire account. If you have an agency account you cannot give one of your customers access to only one project for example. If you want to give your customers access as an agency or the customer asks for this, you need to create separate accounts for them. When this separate account is created, you can contact us to move the project of the customer to this new account. The customer can give you, as agency, access to this new account.