Notice the change in the pronunciation of the “t” in “what”. This is to make it easier to pronounce the following /k/ sound. Instead of pronouncing the “t” with the front of your tongue, use the back of the tongue, then you can go straight to the /k/ without removing your tongue in between the sounds. This takes practice. Also remember you want the weak pronunciation of “can”. The vowel sound is /ə/, not /æ/.
This simple question is another way of saying “How can I help you?”