:not(span) will be used to exlude
Hope this will be helpful for you
.Project {
font-family: 'Lirma';
}
.Project:hover :not(span) {
cursor: default;
text-decoration: underline;
}
<li class="Project" data-modal="myModal_1">
<span id="myBtn_1">
Lirma Type
</span>
<span id="year">
2019
</span>
<div class="Describtion">
<p>
Typedesign
</p>
<br>
<span class="PopUp">Images</span>
</div>
<div id="myModal_1" class="modal">
<div class="modal-content">
<div id="demo" class="carousel slide" data-ride="carousel">
<!-- The slideshow -->
<div class="carousel-inner">
<div class="carousel-item active">
<img class="Image" data-src="Images/Lirma/type.jpg" alt="img" width="100%">
</div>
</div>
</div>
</div>
</div>
</li>