The dictionary form is "알다". "알" is the verb stem. When conjugated to formal present tense the "ㄹ" is dropped and "ㅂ니다" is added. (This is true for all verb stems that end in "ㄹ" for this type of conjugation.) When conjugating to present progressive tense "-고있다" is added to the verb stem. (The "ㄹ" is not dropped for this type of conjugation.)
In english, both "압니다" and "알고있다" would translate to "know", but there's a subtle difference in connotation. "압니다" is generally being aware/having knowledge of something while "알고있다" is more like being aware of something that's relevant specifically in that moment.