I just posted transition meaning in pther thread. Reposting here:
Transition is offered for various durations starting from 3 months to 12 months. Mostly people got 6 or 9 months transition offers. In case they are planning to divest yoir product they will find buyer in meantime. You are required to run business as usual in this duration. In few cases transition offered to plan for site consolidation. So they'll identify new teams at new locations and you need to give KT before finishing your transition period.
Benefits: Transition bonus (50% of base pay for that duration) will be paid at the end. You will also receive your severance, unvested stocks and any other statutory benefits as is.
Drawback: Your transition period can be cut short anytime without any notice. However yoi will be eligible to receive transition bonus for full period as communicated in your initial communication.