A sign-up bonus refers to an offer that casino gives to new customers once they sign up on their site. Casinos use these bonuses to attract new customers and provide them with some funds to start betting. Sign-up bonuses are not withdraw-able and should be used within a timelimit, depending on the casino.
Malaysia is a small South-East Asian country, and a regional economic power horse that attracts new investments to an emerging region. Malaysia is predominantly Muslim country, and all forms of gambling are formally illegal. The ban is loosely enforced. In practice international online and mobile casinos do accept clients from Malaysia.