It is a love lock
A love lock is a padlock that, according to a custom, is attached to bridges, bars or similar fixed objects by lovers to symbolically seal their eternal love.
The padlocks that hang on famous bridges? It has become a great cult to hang a love lock on a bridge with your partner, then toss the key into the river and swear eternal love to each other. In the meantime, countless tourists even make pilgrimages to the most famous love lock bridges, such as in Cologne, Paris or Prague.