Omachi kudasai

こんにちは (Konnichiwa) Abgueguen,

Thank you for your question! 

お待ち下さい (O machi kudasai) is an extremely polite way of saying "please wait." It is much more polite than 待ってください (matte kudasai), and often used in business Japanese.
To use this politer form, just add the honorific particle お (o) before the stem of a verb and then add ください (kudasai).

お (o) VERB STEM + ください (kudasai)

For example, the stem of the verb 待ちます (machimasu) "to wait" is 待ち (machi):

お (o) + 待ち (machi) + ください (kudasai) = お待ちください (omachi kudasai) "please wait."

Here are a few more examples:

お (o) + 食べ (tabe) + ください (kudasai) = お食べください (otabe kudasai) "please eat."
お (o) + 座り (suwari) + ください (kudasai) = お座りください (osuwari kudasai) "please sit."

I hope this helped! Please let me know if you have any other questions.
勉強を頑張ってください！ (Benkyō o ganbatte kudasai!)