How to use Get/streams and 'channel'parameter?

API
2

In the response of /streams?channel=user1,user2, the streams property is an array, so you need to iterate over it.

foreach ($data->streams as $stream)
    echo $stream->channel->display_name;

See https://github.com/justintv/Twitch-API/blob/master/v3_resources/streams.md#get-streams for example output from this endpoint.