Showing ads to you is what pays for many streaming channels.
"No ads" is an extra cost subscription option available on SOME subscription channels. It involves purchasing a subscription to a higher "no ads" subscription tier for each such channel. Look for a "settings", "options", or similar option in each channel then look for an "upgrade", "remove ads", or other similarly worded choice.
Roku Streaming Stick +, 3810X, Ser YH0059427035, wifi - Samsung UN55ES6100
Roku Streaming Stick, 3600X, Ser 5S56D8240827, wifi - JVC EM37T