When people want to become teachers, they must go through a process called certification. The process is different from state to state, but it often requires them to submit a background check, take a certification test, and earn student teaching hours.
In the passage above, what does the word certification mean?

Certification means official 'verification', 'confirmation' or 'attestation'.

Explanation:

In the given passage, the speaker talks about how 'would-be' teachers have to go through a process. This process, called "certification" is required so that "a background check" can be done, and then they have to "take a certification test, and earn student teaching hours".

This "certification" implies the documentation, verification, or confirming the 'educational qualification' of that person. It is the process of legally or officially confirming the person is eligible for the teaching job.

Thus, "certification" in the passage means the official verification, authentication, confirmation, or attestation of that person's background.  

i would say the correct answer is not concrete.

answer: may i ask who shelly is?