To “implement” (implement) means to do something, to put something into action, to take a plan or an idea and actually do it, to make it happen; that's to implement.

We usually talk about implementing plans or strategies.

In this case, Chris wants people to talk about implementing changes, or beginning to make those changes.

He also wants to talk about a timeline for doing so.

A “timeline” (timeline) is a plan showing when someone will do something over a period of time - a week, a month, a year.

At ESLPod.com, for example, we have a timeline for making a certain number of podcasts each week.

Chris is talking about a timeline, or plan, that will tell us when each change will be made.

Next Chris says that as the presentation concludes, or ends, he wants to repeat the key points.

A “key (key) point” is a main idea, or one of the most important ideas.

The key points of this “Business Meetings” course is that English speakers use different vocabulary for formal and informal meetings.

For Chris, the key points are the main ideas that his team has been trying to communicate through the presentation.

In a U.S.business setting, when you are presenting in English to U.S.business people, it is usually very important to repeat your key points as you're ending a presentation, because this helps the audience (the people listening to your presentation) remember what you have said.

Chris's first key point is that the market share is showing a downward trend.

“Downward” (downward) means going down or descending (becoming smaller - becoming less).