The odoo will convert float to float_time like below

# Import math Library

import math

input_value = 0.16666667

hours, minutes = divmod(input_value * 60, 60)

result = '%02d:%02d' % (hours, minutes)

print(result)

Output: 00:10

The number 0.16666667 was obtained from the division between 10 divided by 60 (rounded version of the real amount which is 0.16666666666 ​...). The formula happened because of the relation between minute and second where 1 minute = 60 seconds. Therefore, in this ​ widget="float_time" case, Odoo converted the 10 seconds into the amount determined in minute.​​​​​​​