It depends on how the other element is related to the section.
If it's a descendant element, you can write:
section:hover your-element-selector { display: none; }
If it's a sibling element which follows the section, you can write:
section:hover ~ your-element-selector { display: none; }
If it's somewhere else in the document, then you'll have to use Javascript.
Descendant combinator - CSS: Cascading Style Sheets | MDN[
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General sibling combinator - CSS: Cascading Style Sheets | MDN[
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