This means honesty. Quite a few words being more or less the same thing but they are subtle differences. Satya and Arjava seem to mean the same thing but Arjava means proper conduct. This proper conduct is easy to follow when we are not having any problem. It is only when we are facing adversity that the real test happens. To be straight forward even in such situations is what honesty is all about.
This considered a virtue.
We must show honesty in trusting god without any show.
We must show honesty in reciting his name.
We must show honesty in serving our elders our spiritual leaders.
If we follow honesty in our mundane life and spiritual life we can progress in sadana. I'm not saying this is easy but with trust in God we can achieve it.
If you are wondering about the "honesty in reciting his name", here is a small anecdote.
A sadhu used to recite "sivoham" always. that means "I am siva". Once he was traveling in the Himalayas and as you know it could get very cold there! He was meditating in a clearing and it suddenly got very cold. He tried his best to ignore the cold and keep his mind in the chanting. After a while he could not bear it any more. he changed the chanting to "dehooham" (I am the body) and ran to seek shelter.
The next is kriya. This is love for all creatures in this universe. Thiruvalluvar says
அன்பின் வழியது உயிர்நிலை அஃதிலார்க்meaning a person with out love is just a skeleton on which their skin cover has been put on.
என்பு தோல் போர்த்த உடம்பு
aṉpiṉ vaḻiyatu uyirnilai aḵtilār
eṉpu tōl pōrtta uṭampu
Sri Shankara also says
maṉuṣyatvam mumukṣutvam mahā puruṣacamsrayamin this maṉuṣyatvam means the quality of being human. In this context it is based on love.
turlapam tēvāṉukraha hētukam
Love does not arise out of any sort of infatuation. It comes with unselfish sacrifice and blemishless living. If there is any selfish motive in showing love to any one, there will always be a limit to that and also it is mixed with sorrow.
எத்துணையும் பேதமுறாது எவ்வுயிர்க்கும் தம்முயிர் போல் எண்ணியுள்ளேHe who does not see differences in any life form and would happily consider them as his own, His mind is where my Lord dances in his form of pure knowledge. My mind seeks to serve such a person.
ஒத்துரிமை உடையவராய் உவக்கின்றார் யாரவர் உளந்தான்
சுத்த சித்துருவாய் எம்பெருமான் நடம் புரியும் இடமென நான் தேர்ந்தேன் அந்த
வித்தகர்தம் அடிக்கு ஏவல் புரிந்திட என் சிந்தை மிக விழைந்ததாலோ
ettuṇaiyum pētamuṟātu evvuyirkkum tammuyir pōl eṇṇiyuḷḷē
otturimai uṭaiyavarāy uvakkiṉṟār yāravar uḷantāṉ
cutta citturuvāy emperumāṉ naṭam puriyum iṭameṉa nāṉ tērntēṉ anta
vittakartam aṭikku ēval purintiṭa eṉ cintai mika viḻaintatālō
A learnt Brahmana who is also humble, the cow, the elephant, the dog, the one who eats the dog all are equal in the eyes of a gnani.- Bhagavat Gita 5-18.
Such a realisation comes to one when the love matures. One must be really lucky to serve a person who has matured so much.
If we develop our love it breaks the constraint of the smaller circle "me" , expanding to "us", later on the love encompasses all the living beings, and later still to even the non living things. Such an expansion of the attitude is very important for god realisation. One who is not able to feel the unselfish love cannot realise Go.