Questions & Answers about Сегодня у меня меньше времени, чем вчера.
Russian usually expresses ownership with the construction у + person in genitive (literally “at someone”) rather than with a possessive adjective plus a form of быть.
So:
- У меня есть время. – I have time. (literally: At me there is time.)
In your sentence, the idea is “Today I have less time …”, so Russian naturally uses у меня:
- Сегодня у меня меньше времени…
- Literally: Today at me (there is) less time…
If you said моё время here (e.g. Сегодня моё время меньше), it would sound strange or mean something different, like “my time (period) is shorter today” in a very unusual, almost abstract sense. For everyday “I have time / I don’t have time”, use у меня.