The course now tidies up the irregular verbs, and the first group is the ones taking -go instead of -o for the "I" form.
The -go appears only in the "I" form. Everything else is built normally: tiene, tienes, tienen, tenemos.
Rather than switching vowels like other verbs, these switch the -go to -ga. And unlike the present, that form now covers everybody.
tengo → tenga · vengo → venga
Quiero que vengas · Quiero que lo traigas · No quiero que me distraigas
Answering the phone in Spain you may also hear diga or dígame, tell me. The mood tense on its own is an order, and being positive, the me goes on the end.
Like tener being -tain and poner being -pose, traer hides inside English verbs as -tract.
The irregularity generalises: distraigo, I distract, or me distraigo, I get distracted. Note traer takes an extra i in that form.
Spanish, being effectively modern Latin, is quite prone to it. But the irregularities can be made sense of within themselves, which is why they group together.
Worth recording as the course starts to wrap up. Half the point has been content, teaching you Spanish. The other half has been how to manage it: how to think about the information, how to relate to it, how to find things you think you have forgotten.
Listening actively is how you refresh whatever needs refreshing. In a song or a film, you may catch only the verb endings at first, and identifying what an ending means is the important bit.