The people you meet are simply whoever happens to be online. In practice that means Kiribati and its Oceania neighbours — Nauru and Tuvalu among them — mixed in with strangers from every other continent, which is a fast way to lose an hour.
You will not need a translation app for Kiribati. English is the working language, and the only real adjustment is tuning your ear to an unfamiliar accent for the first minute or two.
Time zones do most of the work in deciding who is awake. Kiribati runs on UTC+12, so its 10pm is 10am in London and 7pm in Tokyo, and evenings are when conversations stretch past the first question.
Nothing at all. Random matching, video, voice and text are open to everyone in Kiribati, whether the conversation runs in English or English, and there is no trial that expires or premium tier holding back the useful parts.
Signing up is not part of it. Anyone in Kiribati can open the page and chat anonymously in English or English; the age confirmation is the only box to tick, and nothing you type becomes an account.
English is the working language in Kiribati, so you can open with a normal sentence and get one back. Matching is worldwide rather than filtered by country, so you will also meet Oceania neighbours who open in something else.
Local evenings. Kiribati keeps time at UTC+12, so roughly 10pm there is the busiest stretch — that works out to 10am if you are in London and 7pm in Tokyo. Matching is global rather than split by country, so this reflects when that corner of Oceania is awake rather than a room of its own.