A text icon usually shows a capital 'T' or a text box, denoting type tools. A developer creating a presentation app could use it for the button that adds or edits written content on slides.
Part of the
Design Tools SVG collection,
in Design.
Download the Text vector as a ready-to-edit .svg file —
it scales to any size without losing quality and can be recoloured in any
vector editor or straight in CSS.