.person {}
.person--female {}
.person__hand {}
.person__hand--left {}
<div class="person person--female">
<div class="person__hand person__hand--left"></div>
</div>
More info about BEM: getbem.com
.person {}
.person--female {}
.person__hand {}
.person__hand--left {}
<div class="person person--female">
<div class="person__hand person__hand--left"></div>
</div>
More info about BEM: getbem.com