if houre == 0 and minute == 0:
                bot.send_message(chat_id, 'букави')
            elif houre == 0 and minute == 0:
                bot.send_message(chat_id, 'букави')
            elif houre == 0 and minute == 0:
                bot.send_message(chat_id, 'букави')

SCHEDULE = {0:[(11,40,'інформатика',l.inf),
               (13,30,'інформатика',l.inf)
              ],
            1:[(11,40,'фізіологія',''),
               (13,30,'щось ще','\nSkype')
              ],
            ...}
...
for sched_hour, sched_min, sched_name, sched_suffix in SCHEDULE[day]:
  alarm_min = sched_min-2
  if alarm_min<0:
    alarm_min += 60
    alarm_hour -= 1
 if hour==alarm_hour and minute==alarm_min:
    end_hour = sched_hour+1
    end_min = sched_min + 20
    if end_min>=60:
        end_min -= 60
        end_hour += 1
   app.send_message(chat_id, f'{sched_name} ({sched_hour}.{sched_min} - {end_hour}.{end_min}){sched_suffix}')
   break

SCHEDULE = [
              [(11,40,'інформатика',l.inf),
               (13,30,'інформатика',l.inf)
              ],
              [(11,40,'фізіологія',''),
               (13,30,'щось ще','\nSkype')
              ],
            ...]
HOURS_IN_DAY = 24
MINUTES_IN_HOUR = 60
MINUTES_BEFORE_ALARM = 2
CLASS_DURATION = 80
def add_time(h, m, dm):
    m += dm
    while m < 0:
        m += MINUTES_IN_HOUR
        h -= 1
    while m >= MINUTES_IN_HOUR:
        m -= MINUTES_IN_HOUR
        h += 1
    h %= HOURS_IN_DAY
    return (h,m)

...

for sched_hour, sched_min, sched_name, sched_suffix in SCHEDULE[day]:
    if (hour, minute)==add_time(sched_hour, sched_min, - MINUTES_BEFORE_ALARM):
        end_hour, end_min = add_time(sched_time, CLASS_DURATION)
        app.send_message(chat_id, f'{sched_name} ({sched_hour}.{sched_min} - {end_hour}.{end_min}){sched_suffix}')
        break

SCHEDULE = [
              {(11,40):('інформатика',l.inf),
               (13,30):('інформатика',l.inf)
              },
              {(11,40):('фізіологія',''),
               (13,30):('щось ще','\nSkype')
              },
            ...]
HOURS_IN_DAY = 24
MINUTES_IN_HOUR = 60
MINUTES_BEFORE_ALARM = 2
CLASS_DURATION = 80
def add_time(h, m, dm):
    dh, m = divmod(m+dm, MINUTES_IN_HOUR)
    return ((h+dh)%HOURS_IN_DAY, m)

...
time_to_alarm = add_time(hour, min, MINUTES_BEFORE_ALARM)
if time_to_alarm in SCHEDULE[day]:
    sched_name, sched_suffix = SCHEDULE[day][time_to_alarm]:
    end_hour, end_min = add_time(time_to_alarm[0], time_to_alarm[1], CLASS_DURATION)
    app.send_message(chat_id, f'{sched_name} ({sched_hour}.{sched_min} - {end_hour}.{end_min}){sched_suffix}')