What does God forbid with this commandment?

It prohibits killing, i.e. taking human life.

Грех ли наказывать по закону преступника смертью и убивать неприятеля на войне?

Не грех. Преступника лишают жизни, чтобы прекратить великое зло, которое он делает; неприятеля убивают на войне, потому что на войне сражаются за Государя и Отечество.

Какие еще грехи запрещаются сею заповедью?

Запрещается содействие убийству каким бы то ни было образом, например, приказанием, советом, помощью; запрещается и все, что беспокоит и сокращает жизнь ближнего, например, гнев, ненависть, ссоры.

Этою же заповедью запрещается соблазн, когда кто примером своим или советом склоняет другого к неверию или какому-либо греху, что называется духовным убийством.

What is commanded by the sixth commandment?

It is commanded to protect the life of one's neighbor and always do him only good.

The Seventh Commandment of God

Thou shalt not commit adultery, thou shalt not commit adultery.

This commandment prohibits adultery, or criminal carnal love between a man and a woman. The same commandment forbids everything that inclines to this sin, for example, immoderate eating, drunkenness, shameless songs, reading bad books, and the like.

What should be done in order not to violate this commandment?

Those who live in marriage need to be faithful to each other, and the rest need to lead a chaste life.

The Eighth Commandment of God

This commandment forbids theft, i.e. taking someone else's property in any illegal way. For example, he who steals,11 robs, or withholds the wages of a worker, sins against this commandment; who receive payment for work, but do not work; Whoever takes someone else's by deception, cunning, for example, gives away a bad commodity instead of a good one, by means of an incorrect weight or measure, does not finish what is sold. (Gehazi, a servant of the prophet Elisha, deceived the Syrian commander Naaman for some money and clothing in the name of this prophet; for this offense he was stricken with leprosy, which had previously been on Naaman.)

What should one be in order not to sin against the eighth commandment?

You need to be hardworking, selfless, merciful, truthful.