Click the arrow next to the icon to open the Insert toolbar, where you can add graphics and special characters to the current sheet.
Tools bar icon:
You can select the following icons:
Inserts a floating frame into the current document. Floating frames are used in HTML documents to display the contents of another file.
Allows a user to insert characters from the range of symbols found in the installed fonts.
Opens a file selection dialog to insert an image into the current document.
Inserts a video or audio file into your document.
Inserts a formula into the current document. For more information open the LibreOffice Math Help.
Inserts an OLE object into the current document. The OLE object is inserted as a link or an embedded object.