Q: Safari quick view

What were you doing when this happened? More information would be helpful.

Hi jelinekcz. None of the current MacBook Air models have a Force Touch trackpad. Lookup or look up, using Quick Look technology, can be engaged with a three finger tap on the trackpad. It is enabled by navigating to  > System Preferences > Trackpad > Point & Click and selecting Look up, if not already selected. Which pop-up overlay is displayed depends upon the context and what element is selected. For a selected word(s), it may be Dictionary, Thesaurus, Apple glossary, Wikipedia, music album info, or a news article. For web page links, it will be an inline preview of a web page. For Finder file icons, it will be a preview of a file's content. This can also be done with a press on the Spacebar key.

Mac Basics: Multi-Touch gestures - Apple Support

Using a Force Touch trackpad - Apple Support

OS X Yosemite: Quick Look files and folders

Quick Look Programming Guide