ложь: command not found

Whilst executing `help' command in a Russian locale bash gives the summary help output.
It also include, quite literary translations of a few built in commands into russian language, e.g.:
ложь - lies, actual command "false"
истина - pure truth, actual command "true"
объявить - proclaim, actual command "declare"
включить - include / turn on, actual command "enable"

First of all, builtins are non-tranlatable and only actually work in C locale. Provided translations, completely lose the commands' meaning and do not provide descriptive hints as it does in English.

It's best to not translate the actual builtin commands. It's ok to translate the arguments e.g. like it's done it:
 [[ выражение ]]
 (( выражение ))
 unalias [-a] имя [имя...]

Full help output:

$ help
GNU bash, версия 4.2.25(1)-release (x86_64-pc-linux-gnu)
Эти команды включены в состав оболочки. Напишите `help' чтобы увидеть этот список.
Напишите `help name' чтобы больше узнать о функции `name'.
Используйте `info bash' чтобы больше узнать об оболочке в целом.
Используйте `man -k' или `info' чтобы больше узнать о командах, не включенных в этот список.

Звездочка (*) возле имени означает, что команда отключена.

 job_spec [&] history [-c] [-d offset] [n] or history -anrw [fi>
 (( выражение )) if КОМАНДЫ; then КОМАНДЫ; [ elif К>
 . filename [arguments] jobs [-lnprs] [jobspec ...] or jobs -x command [a>
 : kill [-s sigspec | -n signum | -sigspec] pid | jo>
 [ arg... ] let arg [arg ...]
 [[ выражение ]] local [option] name[=value] ...
 alias [-p] [name[=значение] ... ] logout [n]
 bg [job_spec ...] mapfile [-n count] [-O origin] [-s count] [-t] [->
 bind [-lpvsPVS] [-m keymap] [-f filename] [-q name> popd [-n] [+N | -N]
 break [n] printf [-v var] format [arguments]
 builtin [shell-builtin [arg ...]] pushd [-n] [+N | -N | dir]
 caller [expr] pwd [-LP]
 case WORD in [PATTERN [| PATTERN]...) COMMANDS ;;]> read [-ers] [-a array] [-d delim] [-i text] [-n n>
 cd [-L|[-P [-e]]] [каталог] readarray [-n count] [-O origin] [-s count] [-t] >
 command [-pVv] command [arg ...] readonly [-aAf] [name[=value] ...] or readonly -p>
 compgen [-abcdefgjksuv] [-o option] [-A action] [> return [n]
 complete [-abcdefgjksuv] [-pr] [-DE] [-o option] [> select NAME [in WORDS ... ;] do COMMANDS; done
 compopt [-o|+o option] [-DE] [name ...] set [-abefhkmnptuvxBCHP] [-o option-name] [--] [a>
 continue [n] shift [n]
 coproc [NAME] command [redirections] shopt [-pqsu] [-o] [optname ...]
 объявить [-aAfFgilrtux] [-p] [имя[=зн> source filename [arguments]
 dirs [-clpv] [+N] [-N] suspend [-f]
 disown [-h] [-ar] [jobspec ...] test [expr]
 echo [-neE] [arg ...] time [-p] pipeline
 включить [-a] [-dnps] [-f имя файл�> раз(а)
 eval [arg ...] trap [-lp] [[arg] signal_spec ...]
 exec [-cl] [-a name] [command [arguments ...]] [re> истина
 exit [n] type [-afptP] name [name ...]
 export [-fn] [name[=value] ...] or export -p typeset [-aAfFgilrtux] [-p] name[=value] ...
 ложь ulimit [-SHacdefilmnpqrstuvx] [limit]
 fc [-e ename] [-lnr] [first] [last] or fc -s [pat=> umask [-p] [-S] [mode]
 fg [job_spec] unalias [-a] имя [имя...]
 for NAME [in WORDS ... ] ; do COMMANDS; done unset [-f] [-v] [name ...]
 for (( exp1; exp2; exp3 )); do COMMANDS; done until COMMANDS; do COMMANDS; done
 function name { COMMANDS ; } or name () { COMMANDS> variables - Names and meanings of some shell vari>
 getopts optstring name [arg] wait [id]
 hash [-lr] [-p pathname] [-dt] [name ...] while COMMANDS; do COMMANDS; done
 help [-dms] [pattern ...] { COMMANDS ; }