The goal of SEO is really to improve your organic search engine ranking and get discovered by the right people. The amount of people visiting your website will increase, leading to more leads, conversions and eventually sales.
There are other more technical things that should improve with SEO services. Things like site speed and meta issues contribute to your overall ranking, so we’d expect those areas to improve.
In addition, you can expect:
Site speed to improve.
Meta issues on the backend of your site to diminish.
Organic search traffic to increase.
Keyword ranking to improve for your targeted keywords.
Overall conversions to increase with time.