Cash and equivalents is the money the company can spend right now: actual bank balances plus "equivalents," parking spots for cash so safe and short-term they are as good as money, think government bills maturing within three months. It is the most honest line on the balance sheet, no estimates, just what is in the till.
Its job is survival and optionality: cash pays the bills when a bad year hits, funds opportunities without borrowing, and buys time in a crisis. Judge the level against the business: a pile too small invites trouble at the first stumble, while a vast pile sitting idle for years can mean management has run out of good ideas for it.