Hi Mariele,
First of all, great work on your project!
To give feedback for your question, I would personally not use the header tag in this situation because, in the context of a real-life website, this is a reusable card that is not used to define the headings or navigation of a page. However, in this context, it is OKAY as your card is the only element on the page.
Also in a header, you will need to have child elements such as heading tags within it so I will add a h1 tag to the name. And I would put any user-defining elements inside it like the image, name and job title.
<header class="title">
<img src="/assets/images/avatar-jessica.jpeg" class="profile-pic">
<h1>
Jessica Randall
</h1>
<span class="description">
London, United Kingdom
</span>
</header>
I hope my feedback will be useful. Again awesome work!