It is indeed essential for a marketing manager or a CEO of any website, to track essential web analytics parameters,if his earnings solely depends on user behavior in his website.I have seen agencies providing ridiculous report to their clients,claiming how well their website is performing.Certain agencies have set their standard parameters that measures the website.But,it is important to know that,every website is different,and hence their measurement parameters differ too!
Basic Google Analytics Metrics You Must Measure
1.Visits :Visits are total number of visitors that come on your website.This number could be both new as well as returning visitor.These visits could be in a specified date range as set by you in Google Analytics.
2.Unique Visitors:These are the first time visitors on your website.Its always great to have new visitors on your website.Getting good number of unique visitors indicates wide reach of your website.It is important you mention a good ratio between unique and returning visitors.Your returning visitors count is equally important,as it indicates proportion of your loyal audience. 
3.Average Time Per Visit This is the amount of time in a session. It is calculated by subtracting time stamp of the first activity in the session minus the time stamp of the last activity of the session. If in a particular time period,there are 700 visits spendng 2300 minutes,then average duration spent on website is 3.29 minutes
4.Bounce Rate Bounce rate percentage is a critical factor in website measurement. It rises , generally,when a visitor leaves your site after viewing only a single page. Bounce rate also increases if there is no activity carried on the page by user and the page is left idle. A 50% bounce rate is about the industry average.When you are a content website,it is important you maintain a minimum bounce rate.If you have a good bounce rate(less),that means your website provides engaging content,and your users are cling to the website. Generally business or service providing websites(Company websites) have higher bounce rate,and this metric does not matter much to them.
5.Acquisition Overview(Paid and Organic Keywords) Here you will find those keywords that gain you traffic through organic means.Organic traffic means the traffic generated through search engines like Google,Yahoo,Bing. In paid keywords section,you will get a detailed report of those keywords that are driving traffic to your website through paid clicks. If you have hired SEO/PPC agency,make sure you ask your SEO /PPC guy to submit this report to you,in order to understand the performance of website.
6.Funnel Visualization 
Visitors Flow is a graphical representation of the paths users took through your site, from the source, to visit different pages, and also helps you to analyze paths they exited your site. Such visualization will help you to understand what factors led your “goal” to remain incomplete. If you have a E-commerce website,that sells watches.Suppose you are selling a high-priced,quality watch that will gain you huge profits.Unfortunately,you are not able to get any conversions on the page,where you have placed the watch.This Visitor Flow visualization will help you to know graphically,user’s behavior on your website and how customers drop away before they land on your desired page. I hope these Google Analytics metrics will help you in grasping your business needs more efficiently.