The users tried to help you here just wanted to know (make sure) you have the api: line in your esphome yaml. As you didn’t post the yaml (How to ask a good question 
Format it properly) this is obviously the first doubt to clear with such a specific error message 
Which makes us wonder what you did. 
(How to ask a good question 
Describe what you changed)
Somewhat expect that for such a ‘clear’ error message there is no further details in the documentation.
In anyway what have probably been the most helpful (and probably the next question raised after confirming the api: line is in the yaml) would be posting your logs 
(How to ask a good question 
Share the logs)
That’s unfortunate but sadly you are not alone in not getting help. While most users are capable of asking “good questions” and even proactively provide yaml/logs (or when asked) there are also others that are struggling with the basics. Often these are the ones not receiving help simply because most people who want to support them have no crystal ball 
.
And while this posted picture mind be funny at first it is to often the case that users don’t read the docs or do a (1 minute) search before posting a question - which often leads to frustrations for the volunteers
This forum is not a helpdesk
The people here don’t work for Home Assistant, that’s an open source project. We are volunteering our free time to help others. Not all topics may get an answer, never mind one that helps you solve your problem.
Beside not everybody
The first post of @ForxPorx is a good example: 
Not much of value… 
Still wouldn’t make it more valuable so instead I pointed out that the “BS” documentation the user was ranting about is crowed sourced and that he got the power to change something (if he actually want’s too - which I indeed really much doubt based on his type of post).
It happens that users are not able to ask (good) question but still want help. So the volunteers here helping others in their free time also have skills “detecting” unasked questions. So for example if a user posts a error message often it indirectly implies a problem even giving no further information. 
Anyway the fast majority in this community luckily acts in good faith and most users are also capable of getting help. 
Promoting How to help us help you - or How to ask a good question more so (specially new) users give it a 5 minute read is one of the few things the supporters can do with the hope improving the quality (and even quantity) of questions asked 