This will depend on how do you define sales enablement at your company, but I will break it out into different categories and all of them combined will lead up to revenue or moving pipeline.
(1) Product training - are reps learning the right messaging and is it landing? You can measure this category in two ways. Leveraging a tool like Chorus.ai or Gong.io, and create trackers on the product and key messaging that you want to track. You can measure how many reps are using your messaging for said product and how well it lands with prospects. On the CS side, you can track the same, and depending on type of release - product adoption and upsell.
(2) Sales training - are reps deploying the right strategies whether they are competitive strategies, middle funnel strategies to move the deal forward? I would leverage trackers, but also feedback from sales managers.
(4) Content - You should leverage a tool like Highspot, ShowPad, or similar tools to see the types of content being leveraged by reps and the types of content that are effective with prospects and customers.
(5) Sales strategy - Is your approach the right approach given the market and persona? How does this translate into the selling motion? Does it reflect the buying motion? Do you have a middle funnel problem where things stuck? Do you have the right advice and CONTENT for each stage of the sales process and sales stage? The main measurement here is sales velocity for New Business. The main measurement is for CS is how effective is your customer journey and do you have the right CONTENT and tool for your CS team to upsell, renew, and increase retention.
I hope this helps.