how many jewish religions are there
There is one Jewish religion like there is one Christian religion and one Islamic religion. Like the other two, there are different sects within Judaism which can sometimes be nearly as different from each other as one is from Islam or Christianity.
Just as Christianity has many many denominations (Catholic, Baptist, Episcopalian, Presbyterian, Morman, etc.) and Islam has several sects (Shia, Sunni, Sufi, etc.), Judaism has three, maybe four, main denominations (Reform, Conservative, Orthodox, and the much smaller Reconstructionist), and many smaller ones. These groups generally differ in how much they do (or do not) follow Jewish law (Halacha) and tradition. Also, there are many sects and subgroups within Orthodox (Modern, Yeshivish, Chassidic, etc.) and there can be many sects within those sects (for instance, there are probably hundreds of different Chassidic groups). These differences may be in traditions, in how much they interact with secular culture, or some can be more political. Then there are the regional groupings, of which there are many (much more than just the Ashkenazi and Sephardi Jews most people are familiar with), with many variations in culture and traditions (though all follow Jewish law if they are Orthodox/observant).